Quotas API

Sits atop quantum.quota.QuotaEngine and quantum.extensions.quotasv2. Extends and replaces quantum.db.quota_db.DbQuotaDriver with QuarkQuotaDriver which is repoze transaction aware (not that DbQuotaDriver wasn't...).
For hierarchal quota checks (ie, rules per group) the plugin must call the QuotaEngine independently of quantum. Implemented in config file in QUOTAS group as quota_X_per_Y.

Requires the config flag:

[QUOTAS]
...
quota_driver = quark.quota_driver.QuarkQuotaDriver
...