merged with master
Add lastModificationTimeMs to Inode

Add lastModificationTimeMs to Inode. Update the Inode, InodeFile and
InodeFolder. Also update tachyon.thrift.ClientFileInfo by edit the
tachyon.thrift and re-generate the java code.
Update the WebUI

Add the Modification_Time to the WebUI
Complete the Last-Modification-Time

Complete the code for lastModificationTime. Update the parent's
modification time when create, delete or rename a file or folder, also
when create a raw table. When write to a file, update the file's
modification time and the file's parent's modification time.
update Spark Compatibility in doc
Remove modification time when write a file

When write to a file, it does not change the metadata of the Inode, so
the lastModificationTimeMs doesn't need update.
Fix the Last-Modification-Time

Update the EditLog to persist the modification time.
Fix the behavior, now the lastModificationTime will be set whenever the
Inode's metadata changes.
Also update the test code of MasterInfo.
Update docs with new tachyon jar paths
Adding javadoc for Users.java and MasterWorkerInfo.java
update docs for running mr
reference tachyon-client instead of tachyon
switched to shade for uber jar on core
switched to shade for client uber jar
removed jar keys
updated docs based off feedback
made all usage of command util exception functions mark with throw
Adding javadoc
Cleanup the Javadocs
lower access level for methods
switched to uri get path to get hadoop path