Fixed the tests warning messages.

Remove unnecessary codes which lead to the following warnning
messages while performing tests:

...mesos/build/src/colors.sh: No such file or directory
...mesos/build/src/atexit.sh: No such file or directory

Review: https://reviews.apache.org/r/72709/
diff --git a/src/tests/balloon_framework_test.sh b/src/tests/balloon_framework_test.sh
index 7d0a4fe..c1d10e1 100755
--- a/src/tests/balloon_framework_test.sh
+++ b/src/tests/balloon_framework_test.sh
@@ -3,10 +3,10 @@
 # This script runs the balloon framework on a cluster using the cgroups
 # isolator and checks that the framework returns a status of 1.
 
-source ${MESOS_SOURCE_DIR}/support/colors.sh
-source ${MESOS_SOURCE_DIR}/support/atexit.sh
-source ${MESOS_HELPER_DIR}/colors.sh
-source ${MESOS_HELPER_DIR}/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 EXISTING_MEMORY_HIERARCHY=$(cat /proc/mounts | grep memory | cut -f 2 -d ' ')
 if [[ -n ${EXISTING_MEMORY_HIERARCHY} ]]; then
diff --git a/src/tests/disk_full_framework_test.sh b/src/tests/disk_full_framework_test.sh
index 62e62cb..ea0deb7 100755
--- a/src/tests/disk_full_framework_test.sh
+++ b/src/tests/disk_full_framework_test.sh
@@ -3,10 +3,10 @@
 # This script runs the disk full framework on a cluster using the disk/du
 # isolator and checks that the framework returns a status of 1.
 
-source "${MESOS_SOURCE_DIR}"/support/colors.sh
-source "${MESOS_SOURCE_DIR}"/support/atexit.sh
-source "${MESOS_HELPER_DIR}"/colors.sh
-source "${MESOS_HELPER_DIR}"/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 MESOS_WORK_DIR=$(mktemp -d -t mesos-XXXXXX)
 export MESOS_WORK_DIR
diff --git a/src/tests/dynamic_reservation_framework_test.sh b/src/tests/dynamic_reservation_framework_test.sh
index c094ed1..070bf4e 100755
--- a/src/tests/dynamic_reservation_framework_test.sh
+++ b/src/tests/dynamic_reservation_framework_test.sh
@@ -14,10 +14,10 @@
   echo "Failed to find MESOS_BUILD_DIR in environment" && \
   exit 1
 
-source ${MESOS_SOURCE_DIR}/support/colors.sh
-source ${MESOS_SOURCE_DIR}/support/atexit.sh
-source ${MESOS_HELPER_DIR}/colors.sh
-source ${MESOS_HELPER_DIR}/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 MESOS_WORK_DIR=`mktemp -d -t mesos-XXXXXX`
 
diff --git a/src/tests/no_executor_framework_test.sh b/src/tests/no_executor_framework_test.sh
index df282ca..29a3e2d 100755
--- a/src/tests/no_executor_framework_test.sh
+++ b/src/tests/no_executor_framework_test.sh
@@ -14,10 +14,10 @@
   echo "Failed to find MESOS_BUILD_DIR in environment" && \
   exit 1
 
-source ${MESOS_SOURCE_DIR}/support/colors.sh
-source ${MESOS_SOURCE_DIR}/support/atexit.sh
-source ${MESOS_HELPER_DIR}/colors.sh
-source ${MESOS_HELPER_DIR}/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 MESOS_WORK_DIR=`mktemp -d -t mesos-XXXXXX`
 
diff --git a/src/tests/persistent_volume_framework_test.sh b/src/tests/persistent_volume_framework_test.sh
index 6488656..f58ac06 100755
--- a/src/tests/persistent_volume_framework_test.sh
+++ b/src/tests/persistent_volume_framework_test.sh
@@ -15,10 +15,10 @@
   exit 1
 
 
-source ${MESOS_SOURCE_DIR}/support/colors.sh
-source ${MESOS_SOURCE_DIR}/support/atexit.sh
-source ${MESOS_HELPER_DIR}/colors.sh
-source ${MESOS_HELPER_DIR}/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 MESOS_WORK_DIR=`mktemp -d -t mesos-XXXXXX`
 
diff --git a/src/tests/test_framework_test.sh b/src/tests/test_framework_test.sh
index 8782e01..119d5db 100755
--- a/src/tests/test_framework_test.sh
+++ b/src/tests/test_framework_test.sh
@@ -14,11 +14,10 @@
   echo "Failed to find MESOS_BUILD_DIR in environment" && \
   exit 1
 
-
-source ${MESOS_SOURCE_DIR}/support/colors.sh
-source ${MESOS_SOURCE_DIR}/support/atexit.sh
-source ${MESOS_HELPER_DIR}/colors.sh
-source ${MESOS_HELPER_DIR}/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 MESOS_WORK_DIR=`mktemp -d -t mesos-XXXXXX`
 
diff --git a/src/tests/test_http_framework_test.sh b/src/tests/test_http_framework_test.sh
index 256655d..4844132 100755
--- a/src/tests/test_http_framework_test.sh
+++ b/src/tests/test_http_framework_test.sh
@@ -14,10 +14,10 @@
   echo "Failed to find MESOS_BUILD_DIR in environment" && \
   exit 1
 
-source ${MESOS_SOURCE_DIR}/support/colors.sh
-source ${MESOS_SOURCE_DIR}/support/atexit.sh
-source ${MESOS_HELPER_DIR}/colors.sh
-source ${MESOS_HELPER_DIR}/atexit.sh
+FILE="${MESOS_SOURCE_DIR}/support/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_SOURCE_DIR}/support/atexit.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/colors.sh" && test -f $FILE && source $FILE
+FILE="${MESOS_HELPER_DIR}/atexit.sh" && test -f $FILE && source $FILE
 
 MESOS_WORK_DIR=`mktemp -d -t mesos-XXXXXX`