CommonUtils: replaced if to switch statement among line 186-198 to make the code more legible.
MasterInfo: corrected mWorkerAddressToId.remove() to remove the key instead of the value.
UnderFileSystemHdfs: replaced the manual array copy with system library function to improve the performance
Merge remote-tracking branch 'amplab/master'
replaced tabs with two spaces.
adjusted the code style.
Merge pull request #58 from jinntrance/master

fixed a bug in MasterInfo and made two improvements.