add TabsToWhitespace utility to tools

TabsToWhitespace (requires Java 7)
Utility automates:
 : Reclusively converting all tabs to four whitespaces
     in java & xml files
 : Removing trailing whitespaces
 : Removing '\r' left from Windows saved files

please see README for usage

Patch Set 2:
 - lol use this utility to remove whitespace
       in README

Change-Id: I703455ce86b1dc421d8831f6aaf2da3fa3fdd7e4
Merge "add TabsToWhitespace utility to tools" into jb-mr1