Small typo in developer guide

[amwright]

Forgive me as I'm a newbie, and trying to learn. I'm following the developer guide and found it wouldn't work. The bug is in the section defining the init.py for the custom identity driver.

Code currently says:
from .tokens import TokensV2

def setup_routes(app, disp):
disp.set_handler('v2_tokens', TokensV2())

I think it's missing the app parameter in TokensV2, should be:
from .tokens import TokensV2

def setup_routes(app, disp):
disp.set_handler('v2_tokens', TokensV2(app))

That fixed it for me.