Allow networks creation with matching CIDRs/ranges

Quick fix.
Cluster with intersection between networks IP address spaces can be created now.
But it will not be allowed to deploy until the user changes network settings (using UI/CLI) appropriately.
Tests are added.

It should be extended with search of free IP address space when desired one is occupied.

Closes-Bug: #1276382

Change-Id: Ia44fa0df07753732c82fc8613af35f16ae940903
Merge "Allow networks creation with matching CIDRs/ranges"