Try to solve exercise 3. from Chapter 9
Merge branch 'master' into develop

'Cause I forgot to work on develop...
Add activation, activation_at and activation_digest to database
Add mailer
Pass test for generating proper activation emails
Activation of users working
Simple refactoring
Forgot password form
Working password reset
Integration test for password reset
Merge branch 'account-activation-password-reset' into develop

Finish branch account activation & password reset
Merge branch 'develop'

Next release