Exercise 7.6.1: Allows gravatar_for helper to take an option size parameter
Exercise 7.6.2: Write tests for the error messages when signing up with invalid parameters
Exercise 7.6.3: Tests for the post-save behavior in the create action
Exercise 7.6.4: Prettify the ugly combination of HTML & ERb using method 'content_tag'
Merge branch 'ruby200'