Fix --no-compile-scalac-color option.

Logic was previously ignoring the --no-compile-scalac-color flag. Since it was
setting that value to False, the other half of the or-condition was being
evaluated and the default True value was used. This ensures that the
--no-compile-scalac-color flag is heeded and overrides whatever is set in
pants.ini.
Merge pull request #15 from leothekim/master

Fix --no-compile-scalac-color flag