Exercise 6.5.1: Add a test for the email downcasing
By commenting out the before_save line in user model, verify that it tests the right thing
Exercise 6.5.2: Verifying that 'self.email = email.downcase' can be written as 'email.downcase!' in 'before_save' callback
Exercise 6.5.3: A valid email regex that disallows double dots in email addresses
So foo@bar..com is disallowed but foo@bar.gov.fr is allowed
Merge branch 'ruby200'

Conflicts:
	Gemfile

Change-Id: I6ddd5d60aba2b80dfdb67ea3d8bc61318b7927ab