initial glusterfs integration deposit
additional changes to make compatible with glusterfs-hadoop plugin 2.1.18
clean up env variables; add unit test for glusterfs
Merge remote branch 'upstream/master'

Conflicts:
	main/src/main/java/tachyon/UnderFileSystem.java
	main/src/main/java/tachyon/UnderFileSystemHdfs.java
resolve conflict and adapt to new changes
update glusterfs-hadoop version
force using hadoop-minicluster 2.3.0
Revert "force using hadoop-minicluster 2.3.0"

This reverts commit 5d82003f56a011062b7095adb863532f0532587b.
exclude glusterfs-hadoop transit dependencies
fix indentation
toggle glusterfs test and add glusterfs test profile. 1) to unit test glusterfs, use command mvn -DGlusterfsMount=/vol -Dhadoop.version=2.3.0, where GlusterfsMount is the Glusterfs mountpoint, 2) to run glusterfs unit test with other tests, use command mvn  -Dglusterfs test
Merge pull request #195 from rootfs/master

adding glusterfs as a new UnderFS