Deprecate quota_items, register resources upon REST initialization

Deprecate quota_items, register resources upon REST initialization

Register 'core' resources when the respective rest controllers are
instantiated, rather than at module load time.

Since in this way there will not be any need to iterate over
quota_items, the option is being deprecated.

This patch does not supply unit tests as the already-existing
routine for registering a resource from quota_items is being
deprecated as well (and was not covered by any unit test beforehand).

DocImpact

Change-Id: Icdb744adfd86d38363239a454ccf04f3c6b9c158
Closes-Bug: #1453322