Merge pull request #1 from amplab/master

merge
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
Added concurrent tests to MasterInfo
Added test for deleting root

We don't allow deleting the root path
Merge pull request #193 from manugoyal/delete-test

Added test for deleting root
fix incomplete rename of UnderfsUtil
Merge pull request #194 from Du-Li/fix-rename-UnderfsUtil

fix incomplete rename of UnderfsUtil
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 documents
create full path
Merge pull request #197 from chenghao-intel/create_full_path

Create local folders if parent path doesn't exist
A couple minor fixes and cleanups

There were more, but I was too slow, and other people already fixed them :)
Minor improvements to resilience of Heartbeat Thread

Improvements include:

- The HeartbeatThread is now always daemonic, so it will not prevent the
Master or Worker from exiting.
- Any exceptions that propagate from the HeartbeatExecutor will be printed.
- mIsShutdown was made volatile, and Thread.interrupt() used, to ensure
  timely shutdown of the thread. Note that either one is sufficient, but
  without either of them, the JVM does not guarantee this thread ever exits.
Merge pull request #199 from aarondav/heartbeat

Minor improvements to resilience of Heartbeat Thread
Fix indentation
update glusterfs-hadoop version
force using hadoop-minicluster 2.3.0