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
update homepage
tweak homepage
tweak documents
update document
add comments and unit tests to TachyonFS.get()
add utils addleadingzero with unit tests
add unit tests for mkdir. add more comments
reorg masterinfotest
add getPathWithoutSchemaTest util