Closes#1605
* Move styling for `#signup`, `#forgotten`, `#reset`, `#login`, `#usermenu` and `#notifications` to classes
No IDs have been added or removed, so any events shouldn't be affected and it passes all tests.
Closes#288
* I use SendGrid for sending the emails, and it works fine (provided you supply the correct credentials in `config.mail` in `config.js`)
* Generates a random 12 char long alphanumeric password, replaces user's pw, and sends an email about it.