mGerrit: add color to code diff dialog

This formatts removed code to red and added code to green.
We also replace all unicode and respect whitespace formatting

Patch Set 2: layout adjustments
Patch Set 3: remove extra line returns
Patch Set 4: begin adding Diff object class
             introduced \t highlighting... maybe
             (there is a tab in this commit, testing 123)
Patch Set 5: utilize Diff class better \t and whitespace detection
Patch Set 6: whitespace/tab detection
Patch Set 7: update example
Patch Set 8: account for excaped '\'
Patch Set 9: finally fix trailing whitespace and tab detection!
Patch Set 10: use GerritTask for communications
              colorize all syntax for diff

Change-Id: Ifc45a6a6f4968bc186c51b06aa3c0353072f18cd