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.
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.
made all usage of command util exception functions mark with throw
switched to guava and removed throw functions
exceptions
Fix the Last-Modification-Time

Use opTimeMs in the EditLog.
Call System.currentTimeMillis() in MasterInfo instead of
MasterServiceHandler.
Fix the Last-Modification-Time

Use opTimeMs both in EditLog and MasterInfo.
Merge branch 'master' into throws
fixed logic issues with error handling
make guava a top level depdency
switch version to 0.6
Merge pull request #289 from dcapwell/version/6

switch version to 0.6
format
Merge branch 'master' into throws
remove guava from all other deps
Merge pull request #279 from dcapwell/throws

Switched to guava and java std apis for exception throwing
format the code for switching to guava PR; add import order to doc.