Some refactoring of tests.
Added User model.
Added "annotate" gem.
Started adding user model tests.
Added name and email validation for users.
Fixed email validation accepting "+" and "_" characters in domain name.
Added uniqueness constraint to user email validation.
Added unique email index for users.
Downcase email addresses to prevent casing issues at the DB validation level.
Added password_digest attribute to users.
Added password and password_confirmation attributes to user model.
Added tests for password authentication.