Functional test for ipv6 subnet can handle multiple allocation pools

- also added import of plugin.py since quotas won't be imported without it if test run individually
    - eample `tox -e py27 -- tests/funcation/plugin_modules/test_subnets.py` will fail without the import line
    - add #noqa so flake8 doesn't complain

RM9834
Limit allocation_pools per subnet

Creates a quota for allocation pools per subnet.
The update case is ignored because we don't allow
subnet updates anyway.

RM#9974
Also fixes RM#9874
Merge pull request #253 from rackerlabs/up_alloc_pool_quota

Limit allocation_pools per subnet
RM100020

Revisions to ConnectionPools and SSL connections based on testing
Merge pull request #254 from Cerberus98/rm100020_work

RM100020
Adding unit tests for multiple fixed ips

Also includes minor cosmetic cleanup on the test modules. RM9643
Merge pull request #255 from insequent/fix_fixed_ip_allocation

Adding unit tests for multiple fixed ips
Merge pull request #252 from jmeridth/rm9834

Functional test for ipv6 subnet can handle multiple allocation pools