Implement Moip using moiper gem
Add expectations for Payment checkout in MessagesController#pay
Controller tests to validate payment notifications and successful callback
Tests of Moip checkout process
Use Message#confirm! method in project tests

Fixes broken test.
Merge remote-tracking branch 'origin/master' into moip

Conflicts:
	Gemfile.lock
Update gems and remove paypal-express
Merge branch 'moip'