Fix validation in Cucumber
Remove dead code
Simplify cookbooks URL handling to make it consistent

 - switch from regexp routes to regular patterns
 - move finding cookbook/file to a helper that will throw a 404 if invalid or not found on server
 - make file_types a frozen constant
 - serve recipe files at `/cookbook/:cookbook/recipes/foo.rb` so that URL matches on-disk path to recipe file
Attempt to untangle cookbook views spaghetti