Added gem omniauth-facebook
Added implementation base to auth using fb
Added method to auth using facebook
Added check for exists groups for user
Renamed to use new method name for facebook auth
Removed validate of team and added option to link account with facebook
Added gem dotenv-rails
Added .env in gitignore
Added sample for .env
Changed to use environment variable on secrets
Changed to use environment variable on facebook auth
Added SECRET_KEY to travis
Added authentication using Facebook