Quota Templates

Currently when an operator creates a new user, is not able to set up quotas based on a predefined template.
In order to accelerate this process and make it less error prone, I propose to add a capability to create quota templates that can be used to set up user quotas in one step.

This use case that explains this concept:

Precondition:
1. The operator defined 2 quota templates called "for dev" and "for test"
The template "for dev" has the following resources and limits: 2 instances, 16GB RAM, 6 cores and 128GB Disk
The template "for test" has: 8 instances, 16GB RAM, 8 cores and 32GB Disk

Normal Scenario:
1. A new user requires to create some instances, he needs machines for development tasks.
2. The operator fill the first two workflow tabs in horizon with the user info and groups.
3. The operator goes to the quotas tab, he selects the template "for dev" and all the quotas for this template are displayed.
4. The operator does not make any change in the quotas tab and finalize the user workflow.

Notes:
1. The template will not be associated to the user once it is created, the template is just used to group quota values that are use often and depending on the kind of users that are created.
2. The quota templates that are created belong to a projects and cannot be used from another one.

Out of scope:
. Default quota template: set a template as default for a project