First iteration of ExtraStorage refactor
Add some missing files
Use new refactored ExtraStorage system when creating a new account
Use new ExtraStorage system when requesting a mail change

Use correct method names on MailChangeToken too
Add mongo backend
Merge remote branch 'origin/extrastorages2' into extrastorages

Minor adaptions to our classes

Conflicts:
	config-templates/module_userregistration.php
	lib/ExtraStorage.php
	lib/ExtraStorage/Redis.php
	lib/Registration.php
	www/changeMail.php
	www/newUser.php
Actually add support for MongoDB

Also supports token expiration
Merge pull request #5 from OpenMOOC/extrastorages

Support both MongoDB and redis