Use correct project/user for quotas

This fixes the compute manager to ensure the proper project_id/user_id
is used when making quota calls by converting most of the compute
manager code to use the new objects. This does not change the RPC
messages to the manager, yet.

Change-Id: I50601d12edef735f3c01ad73445e0826d05efc51
Closes-bug: 1271541
Merge "Use correct project/user for quotas"