create a concern to handle with some omniauth methods
remove some unused code :)
fix broken spec on PaymentEngines
remove contributed_by and contributed_projects from project and user and added the contributed_projects via has_many ;)
Merge branch 'master' into added_some_concerns
Merge pull request #754 from devton/added_some_concerns

Added some concerns and refacts <3
remove href='' because we already use defined?(href) to check if href is valid
Merge pull request #755 from devton/bugfix/fb_like-13476997

remove href='' because we already use defined?(href) to check if href is...