Adds tests covering Swift's Account Quota middleware

The execution of the tests is conditional to a setting declared
in the config file.

There are 2 tests:
 + User uploads an object smaller than the quota successfully
 + User fails to upload an object larger than the quota

Note that this test assumes that the admin account has the
ResellerAdmin role.

Change-Id: I00dd1b88d4d9b65b4c6f5b9cc6b1c8704bdc9d8b
Merge "Adds tests covering Swift's Account Quota middleware"