Ensuring that Heroku does not install gems within the Bundler :development group
switch sqlite3 to mysql in developement/test env
deploied on heroku: see http://paymill-on-rails.herokuapp.com
Merge branch 'master' into heroku-deploy
modified: config/initializers/paymill.rb
config.serve_static_assets = true (see config/environments/production.rb)
modified:   README.rdoc
extracting paymill keys to env variables for heroku set up