Merge pull request #2 from dsuppiger/master

Add support for Redis database.
Update dependecy versions.
Change the type of IDs from sting to a strongly typed struct.
Rename (Redis/Mongo)Controller to (Redis/Mongo)UserManController.
Add some additional controller methods for more fine grained control.
Convert User/Group to structs and remove the explicit (to/from)Bson methods.
Refactored RedisUserManController to use redis idioms. Also fixed various bugs.