Bug fix for broken loading gif on Heroku

* closes #115
* adding rails_12factor gem
* one line to configuring production environment
* removing capybar-wekit gem: we're not using it;
  it won't install on certain laptops, which prevents
  deploy to Heroku
Merge branch 'master' into bug-115
Merge pull request #117 from LightningLord/bug-115

Bug 115: ajax loading gif fix