Update all Rails 4.1.0 references in guides to 4.1.1 [ci skip]

This updates all the Rails 4.1.0 references in the guides to 4.1.1. I made this change within the guides themselves and the Rails app that is included in `guides/code/getting_started`. I also updated `sass-rails` to version 4.0.3, which is the version that ships with Rails 4.1.1.