Rework format-webkitpy to use single-quoting for chromium, add more args.

In addition to changing the default for the chromium coding style to
use single-quoted string literals instead of double, this reworks the
structure of the program to be a bit clearer, and adds command line
args to toggle on and off the autopep8 reformatting and the string literal
reformatting.

TBR=eseidel@chromium.org

Review URL: https://codereview.chromium.org/555283006

git-svn-id: svn://svn.chromium.org/blink/trunk@181767 bbb929c8-8fbe-4397-9dbb-9b2b20218538