Developers can see Guatemala Tariff Rates [81716168]

Did you need to make this change in order to get your local env working? @kjubichan (Yury) and I removed the "ruby-" prefix to support ruby version managers other than rvm (i.e. rbenv). rvm worked for me without the prefix (its [documentation seems to suggest it should](http://rvm.io/workflow/projects#project-file-ruby-version) although it's a bit unclear).