Changed User.create signature to accept a hash, added a couple of utilit...

...y functions as well, also added a new hook `filter:user.create` .

__EDIT__:  also added a new config `use_proxy` - I wasn't sure where exactly you would prefer that config to live, feel free to either move it or suggest a better place (db maybe?) - but it does require a restart, so I figured the `config.json` is not a bad idea.