Add CPF_CNPJ gem to generate random CPF for tests
Remove webhooks spec
Add styles to Thanks page
Create MailWorker that will be forked after Unicorn preload_app action

This way, we don't need a worker on heroku to do it.
Create invite system and add specs for Subscriptions and Subscribers

- Create invite table
- Create relationship between users and invitees
- Add invite session key on projects#index
- Create invite relation when creating users
- Test mail worker on subscription_spec
- Add model spec for User and Invite
Add facebook share TAF

With his invite code.