Workaround for Rainbow dependency, see rubocop/rubocop#763.

Author: dblock

Rakefile

@@ -15,6 +15,7 @@ RSpec::Core::RakeTask.new(:rcov) do |spec|
 end
 
 task :spec
+require 'rainbow/ext/string' unless String.respond_to?(:color)
 require 'rubocop/rake_task'
 Rubocop::RakeTask.new(:rubocop)