Fixes #11 Apps are failing to run on cluster (#12)

* Created new property so that 'fs.defaultFS' is set in hadoop
  config that is passed to YarnTwillRunnerService
diff --git a/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnEnv.java b/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnEnv.java
index dcf2041..2c76fec 100644
--- a/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnEnv.java
+++ b/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnEnv.java
@@ -82,6 +82,7 @@
       yarnConfig = new YarnConfiguration();
       yarnConfig.set("mapreduce.framework.name", "yarn");
       yarnConfig.set("yarn.resourcemanager.hostname", getYarnResourceManager());
+      yarnConfig.set("fs.defaultFS", getDfsRoot());
     }
     return yarnConfig;
   }
@@ -96,6 +97,10 @@
         FluoYarnProperties.ZOOKEEPERS_DEFAULT);
   }
 
+  public String getDfsRoot() {
+    return props.getProperty(FluoYarnProperties.DFS_ROOT_PROP, FluoYarnProperties.DFS_ROOT_DEFAULT);
+  }
+
   public int getWorkerCores() {
     return Integer.valueOf(props.getProperty(FluoYarnProperties.WORKER_NUM_CORES_PROP,
         FluoYarnProperties.WORKER_NUM_CORES_DEFAULT));
diff --git a/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnProperties.java b/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnProperties.java
index 4d34647..d61dca6 100644
--- a/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnProperties.java
+++ b/core/src/main/java/org/apache/fluo/yarn/core/FluoYarnProperties.java
@@ -26,8 +26,10 @@
   // General properties
   public static final String YARN_RESOURCE_MANAGER_PROP = YARN_PREFIX + ".resource.manager";
   public static final String ZOOKEEPERS_PROP = YARN_PREFIX + ".zookeepers";
+  public static final String DFS_ROOT_PROP = YARN_PREFIX + ".dfs.root";
   public static final String YARN_RESOURCE_MANAGER_DEFAULT = "localhost";
   public static final String ZOOKEEPERS_DEFAULT = "localhost/fluo-yarn";
+  public static final String DFS_ROOT_DEFAULT = "hdfs://localhost:8020/";
 
   // Worker properties
   public static final String WORKER_INSTANCES_PROP = YARN_PREFIX + ".worker.instances";
diff --git a/distribution/conf/fluo-yarn.properties b/distribution/conf/fluo-yarn.properties
index 996b132..0af7bf8 100644
--- a/distribution/conf/fluo-yarn.properties
+++ b/distribution/conf/fluo-yarn.properties
@@ -25,15 +25,21 @@
 ## Zookeeper connection string specifying host and chroot where Fluo YARN launcher stores data.
 ## A chroot directory suffix (with max depth of 1) must be specified but doesn't need to be named '/fluo-yarn'.
 #fluo.yarn.zookeepers=localhost/fluo-yarn
+
 ## YARN resource manager hostname. Should match 'yarn.resourcemanager.hostname' property in Hadoop's yarn-site.xml
 #fluo.yarn.resource.manager=localhost
 
+## HDFS root path. Should be prefixed with 'fs.defaultFS' property in Hadoop's core-site.xml
+#fluo.yarn.dfs.root=hdfs://localhost:8020/
+
 ## Oracle properties
 ## -----------------
 ## Number of oracle yarn instances
 #fluo.yarn.oracle.instances=1
+
 ## Max memory of Oracle yarn containers (in MB)
 #fluo.yarn.oracle.max.memory.mb=512
+
 ## Number of Oracle virtual cores
 #fluo.yarn.oracle.num.cores=1
 
@@ -41,11 +47,13 @@
 ## -----------------
 ## Number of Worker instances
 #fluo.yarn.worker.instances=1
+
 ## Max memory of worker YARN containers (in MB). If YARN is killing worker processes consider
 ## increasing twill.java.reserved.memory.mb (which defaults to 200 and is set in yarn-site.xml).
 ## The twill.java.reserved.memory.mb config determines the gap between the YARN memory limit set
 ## below and the java -Xmx setting.  For example, if max memory is 1024 and twill reserved memory
 ## is 200, the java -Xmx setting will be 1024-200 = 824 MB.
 #fluo.yarn.worker.max.memory.mb=1024
+
 ## Number of worker virtual cores
 #fluo.yarn.worker.num.cores=1