Do not accept invalid keys in quota-update

Check if the keys are valid and respond with HTTPBadRequest
when they are not.

Found a spot in wsgi where we were trying to use xml namespace
as data for the payload, we need to skip them when converting
to json

Fix for LP# 1064864

Change-Id: Ic4a68047adf3ccf2dbac669b1b66d73bfe4d58de
Merge "Do not accept invalid keys in quota-update"