Gems update

Due to recent gems update, current bundle (RC12) is not passing. Updated gems consequently :

* Rails : 3.2.12
* Devise : 2.3.3
* Net-scp : 1.1.0
* Heroku-API : 0.3.8
* Fog : 1.10.0

This pull request has to be linked with the one made on locomotive-heroku repository.