This patch fixes quota management APIs in the Pecan framework.
To this aim:
1) an ad-hoc pair of collection/item controllers are introduced
for the quota resource; as the new controllers have been added
in a separate module, the neutron.pecan_wsgi.controllers.utils
module has been added as well for helpers, routines and classes
used by all pecan controllers;
2) the quota API extension is made pecan-aware, meaning that it
simply returns a Pecan controller instance rather than deferring
the task to the startup process that builds controllers using the
home-grown WSGI framework ext manager;
3) the quota resource is now "almost" a standard neutron resource;
unfortunately since it does not yet have its own service plugin a
special provision is made in the attribute population hook in
order to ensure the object is loaded for allowing correct
policy enforcement.
4) Functional tests for the quota controller have been added.
Closes-Bug: #1505843
Change-Id: I44a1fd73f678e493d5b1163e5f183d9efdc678ac
5fe6f8015a