Fix some email formatting issues

When I first signed up, the email looked like this:

![Before](https://f.cloud.github.com/assets/14028/378877/caa7b01e-a56c-11e2-9994-02efbac06dfa.png)

The circles highlight the bits which caught me eye. I've fixed bits, and made the templates a little more consistent and corrected some syntactic mistakes. Here's the confirmation email now:

![After](https://f.cloud.github.com/assets/14028/378883/f9bf8c0a-a56c-11e2-8565-7e0bc6571974.png)