Upgraded rails to 4.1
Using rails 4.1 secret.yml
Merge pull request #35 from coopdevs/feature/upgrade-rails-to-4.1

Upgrade Rails to 4.1
Added ActionMailer configuration
Added user mailer
Merge pull request #17 from coopdevs/add-action-mailer

Add action mailer
Added Invitation model
Added Invitation serializers
Added Invitation controller and routes
Added Invitation index and create actions
Removed JSON parameters wrapping
Added Invitation policy
WIP