Add ignores for bower-rails

bower-rails integrates bower.io into Rails, it allows you to have everything in a Bowerfile and install all vendor assets easily.

Rails.gitignore

@@ -24,3 +24,8 @@ config/secrets.yml
 
 # unless supporting rvm < 1.11.0 or doing something fancy, ignore this:
 .rvmrc
+
+# if using bower-rails ignore default bower_components path bower.json files
+/vendor/assets/bower_components
+*.bowerrc
+bower.json