Test environment deployment with public (API) network separated from floating

Test environment deployment with a special network for public Openstack API endpoints. The feature should be available from Fuel GUI while creating a new cluster and require a separate L3 network with a working gateway. Base test scenarios look like the following:

Test #1: Deploy environment with enabled DMZ network for API
    (pre-step) 0.1 Add new fuel-devops template with additional routed network for DMZ to the fuel-qa code
    (pre-step) 0.2 Add new setting to fuel-qa which activates prepared in #0.1 fuel-devops template and enables DMZ while new cluster is created (e.g. ENABLE_DMZ which is False by default)
    1. Create new environment (like in BVT)
    2. Run network verification
    3. Deploy the environment
    4. Run network verification
    5. Run OSTF
    6. Reboot cluster nodes
    7. Run OSTF
    8. Create environment snapshot (libvirt)

Test #2: Check that security rules are properly applied for DMZ network
    1. Revert snapshot from previous test
    2. Try to access public horizon from instance