140 newuser email

* Fixes #140
* Collect an e-mail address at user creation
* At user creation, put account in an "unverified" state and send a verification e-mail to the user
* Add a verify.html page and backend code to verify accounts using the verification key sent in the e-mail
* Don't allow unverified users to login, and don't show unverified users as possible opponents in the create_game dialogue (but it's still legal to create a game against an unverified user, it's just not necessarily going to lead to your getting a playable game, so we don't show the option in the UI)
* Jenkins: http://jenkins.buttonweavers.com:8080/job/buttonmen-cgolubi1/144/
* Requires a database reload