Changed email validation to use marrow.mailer

Signed-off-by: Tyler O'Meara <Tyler@TylerOMeara.com>
Catch mongodb errors thrown when saving email address changes, and add email taken check to the signup page.

Signed-off-by: Tyler O'Meara <Tyler@TylerOMeara.com>
Merge pull request #114 from Acidity/feature/emailFix

Changed the email validation to use marrow.mailer...