Merge pull request #167 from Cerberus98/master

Fixed tenant_id and device_id filtering.
Default net assignment

Adds default network assignment to Quark, along with yanking out
repoze.tm2 for compatibility while reinstating the standard
sqlalchemy-style transaction sessions to eliminate the race condition in
mass-assigning IP addresses under load.

Also fixes a typo with ipam_reuse_after which was previously, and
incorrectly, a boolean config value.
Merge pull request #168 from Cerberus98/transaction_merge

Default net assignment
Quark ipam strategies implemented

Adds configurability to quark ipam adding three options: "ANY"
(default), "BOTH", and "BOTH_REQUIRED". Version-based IP selection
occurs per-network based on this setting.

Implements RM#2606
Merge pull request #170 from mpath/ipam_strats

Quark ipam strategies implemented
Adds Network extensions resource

Exposes the IPAM strategy associated with a network through a new
Networks API extension. Subsequent patches will update the API extension
to allow the strategy to be set on network create.