[WIP] Bz1133132 add new models to reporting

Adding several cloudy models to reporting:

* Flavors
* Availability Zones
* Security Groups
* Cloud Tenants
* Cloud Resource Quotas
Maybe rename: 

* `class_by_assoc_class_name` to `association_class`
* `class_by_assoc_name` to `class_from_association_name`.

That way there's something that represents the class obtained from constantizing the association name (`ExtManagementSystem` derived from `:ext_management_system`), and something else that represents the actual class of the association (`EmsCloud`).

Then the variables are so closely named, and they no longer imply that they're names, and instead they better imply that they're actual classes.