Fix color output for rspec when running via rake.
Force rainbow-1.1.4 as dependency of rubocop, since it is incompatible
with 2.0.0.  Currently, rubocop's gemspec, doesn't restrict the 2.x
gem for rainbow.

See bbatsov/rubocop#762 for more details.
Merge pull request #129 from seomoz/cbf/fix-rspec-color

Fix color output for rspec when running via rake.