Steamless account creation

[laverdet]

Thanks for the implementation! If you don't mind there's a few minor things that need to be updated:

• The email assignment should go through context.authenticateForProvider / User.findProvidersForUser. This allows the user to actually login via email instead of their account name. There's some sample code in the steam provider.
• I'd like to see a configure option to disable registration because I don't feel like dealing with a ton of fake accounts on xxworld

Let me know if you don't feel like updating the diff and I can take care of it after merging.

[bastianh]

I have updated the branch, let me know what you think

[laverdet]

Thank you!