Revert "hadoop (jobtracker) wants fully-qualified hostnames (ie trailing "." suffix)"
 This reverts commit eb187b075691c09abdf3c83d8abe6e84e35ba8e4.

Hadoop-2.2.0 doesn't seem to work with fully-qualified hostnames.
 reference: http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-common/ClusterSetup.html#Hadoop_Rack_Awareness