Rally ignores subnet quotas

[Valentyn Khalin]

Description:
Whyu I tried to remove subnet quotas in Rally scenario I've reached error which means that subnet quotas were not applied from it.

Steps to reproduce:
- create new scenario.yaml with code below:
```
---
  NeutronNetworks.create_and_delete_subnets:
    -
      args:
        network_create_args: {}
        subnet_create_args: {}
        subnet_cidr_start: "1.1.0.0/30"
        subnets_per_network: 2
      runner:
        type: "constant"
        times: 10
        concurrency: 5
      context:
        network: {}
        users:
          tenants: 1
          users_per_tenant: 1
        quotas:
          neutron:
            network: -1
            subnet: -1
```
- ssh to one of Openstack controllers
- do ". openrc" in your terminal to define variables needed
- do "neutron quota-update --subnet 1" to define quota for all tenants as I understand (or admin)
- start Rally benchmark with scenario.yaml
- do "neutron quota-update --subnet 10"
- start Rally benchmark with scenario.yaml once again and compare results

Expected result:
- tests passed/failed not because of quotas

Actual result:
When you first run scenario.yaml with "neutron quota-update --subnet 1" applied you get an error:
```
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/mcv_consoler/plugins/runner.py", line 248, in run_batch
    if self.run_individual_task(task, *args, **kwargs):
  File "/usr/local/lib/python2.7/dist-packages/mcv_consoler/plugins/rally/runner.py", line 731, in run_individual_task
    task_failed = self._run_rally_on_docker(task, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/mcv_consoler/plugins/rally/runner.py", line 612, in _run_rally_on_docker
    network = self.create_test_network()
  File "/usr/local/lib/python2.7/dist-packages/mcv_consoler/plugins/rally/runner.py", line 329, in create_test_network
    'ip_version': 4}})
  File "/usr/local/lib/python2.7/dist-packages/neutronclient/v2_0/client.py", line 793, in create_subnet
    return self.post(self.subnets_path, body=body)
  File "/usr/local/lib/python2.7/dist-packages/neutronclient/v2_0/client.py", line 365, in post
    headers=headers, params=params)
  File "/usr/local/lib/python2.7/dist-packages/neutronclient/v2_0/client.py", line 300, in do_request
    self._handle_fault_response(status_code, replybody, resp)
  File "/usr/local/lib/python2.7/dist-packages/neutronclient/v2_0/client.py", line 275, in _handle_fault_response
    exception_handler_v20(status_code, error_body)
  File "/usr/local/lib/python2.7/dist-packages/neutronclient/v2_0/client.py", line 91, in exception_handler_v20
    request_ids=request_ids)
OverQuotaClient: Quota exceeded for resources: ['subnet']

```

[Andriy Kurilin (andreykurilin)]

Sorry for late reply, but I did not see any rally execution in your trace. It looks like it is your own code tries to create some kind of network with subnet.