Resolved duplicate inclusion of HADOOP_CLIENT_OPTS
Updated protobuf version to 2.4.1 from prior alpha of 2.4.0a
Added YARN_CLIENT_OPTS to arbitrary commands, and added helpful "dryrun" option
Fix problems with preferring YARN_CONF_DIR over HADOOP_YARN_HOME/conf over other HADOOP defaults
ignore .junit files created in the "build" directory, and ignore Mac OS desktop file .DS_Store