Add a '--skip-routes' flag for the Controller generator.

This way it is possible to skip the addition of the 'get "foo/bar"' routes when generating a controller.
`return unless options[:skip_routes]` at the top might be easier to read / less commit history churn. See also [1](http://blog.bengarney.com/2013/05/11/flatten-your-conditionals/), [2](http://blog.codinghorror.com/flattening-arrow-code/).