Fix deprecated syntax for rspec > 3.1

[rrrrrrmb]

While running tests with rspec>3.1 it fails due to NoMethodError: undefined method `color_enabled=' This is because the config options changed after rspec >3.1. This PR introduces changes so that this works when running tests with rspec > 3.1 . I know you haven't been active for quite a long time. But I hope you'll include this in your next release :)