ARIA-281 Update click library version

Updated click library version to a newer version.
This will also make it compatible in the same environment with the
pip-tools library which uses click too and requires the newer version.

Additional changes:
 - Removed PyYAML dependency from requirements.txt (leftover)
 - Disabled default goal of Makefile
diff --git a/Makefile b/Makefile
index a857ca7..cb4b58f 100644
--- a/Makefile
+++ b/Makefile
@@ -20,9 +20,12 @@
 EASY_INSTALL_PTH = $(VIRTUAL_ENV)/lib/python2.7/site-packages/easy-install.pth
 PYTHON_VERSION = $$(python -V 2>&1 | cut -f2 -d' ' | cut -f1,2 -d'.' --output-delimiter='')
 
-.DEFAULT_GOAL = install
+.DEFAULT_GOAL = default
 .PHONY: clean install install-virtual docs test dist deploy
 
+default:
+	@echo "Please choose one of the following targets: clean, install, install-virtual, docs, test, dist, deploy, requirements.txt"
+
 clean:
 	rm -rf "$(DIST)" "$(HTML)" .tox .coverage*
 	-find . -type f -name '.coverage' -delete
diff --git a/requirements.in b/requirements.in
index 54e8714..d205c7a 100644
--- a/requirements.in
+++ b/requirements.in
@@ -28,7 +28,7 @@
 bottle>=0.12.0, <0.13
 Fabric>=1.13.0, <1.14
 setuptools>=35.0.0, <36.0.0
-click>=4.1, < 5.0
+click>=6.0, < 7.0
 colorama>=0.3.7, <=0.3.9
 PrettyTable>=0.7,<0.8
 click_didyoumean==0.0.3
diff --git a/requirements.txt b/requirements.txt
index 8551c65..6cf2ade 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@
 # This file is autogenerated by pip-compile
 # To update, run:
 #
-#    pip-compile --output-file requirements.txt requirements.in
+#    pip-compile --output-file ./requirements.txt ./requirements.in
 #
 # Since the tool we are using to generate our requirements.txt, `pip-tools`,
 # does not currently support conditional dependencies (;), we're adding our original
@@ -25,7 +25,7 @@
 bottle==0.12.13
 cachecontrol[filecache]==0.12.1
 cffi==1.10.0              # via cryptography
-click==4.1
+click==6.7
 click_didyoumean==0.0.3
 clint==0.5.1
 colorama==0.3.9
@@ -48,7 +48,6 @@
 pyasn1==0.2.3             # via paramiko
 pycparser==2.17           # via cffi
 pyparsing==2.2.0          # via packaging
-pyyaml==3.12
 requests==2.13.0
 retrying==1.3.3
 ruamel.ordereddict==0.4.9  # via ruamel.yaml