Use 12factor heroku gem

So we wont have problems setting the wrong flag for serve assets, like it happen yesterday
fix PR text in home

I'm not sure but isn't this the right way? :) "What `are` you upto?" right? :D
added line-height to footer ul elements to make them of same height
Merge pull request #891 from steverob/patch-3

fix PR text in home
Merge pull request #892 from steverob/footer-alignment

added line-height to footer ul elements to make them of same height
not requiring rspec when rails loads
showing past 24pr events
infinite scroll on projects
Merge pull request #893 from steverob/donot-require-rspec

not requiring rspec when rails loads
Merge pull request #894 from steverob/past-events

showing past 24pr events
Use rails_serve_static_assets 0.0.3
Whitespace
Moved event view duplication into a partial
Merge pull request #887 from arthurnn/rails_12factor

Use 12factor heroku gem
Merge pull request #895 from acrogenesis/infinite-scroll

infinite scroll on projects
Merge pull request #896 from 24pullrequests/event-partial

Moved event view duplication into a partial
Updated ruby-progresbar