Update emails to match designed templates

[polastre]

Emails were designed to look like this. They don't. Fix their code to be in line with the mailchimp templates (https://github.com/mailchimp/email-blueprints/blob/master/responsive-templates/base_boxed_basic_query.html)

This is a follow on to #37.

Minor exception:

• The shield in the button will be almost impossible in email (using text/css), so omit it for now.

  Email 1 -- System critical emails (eg login)

Email 2 -- Notification emails (and system non-critical)

[dutchashell]

;)