[1247283] Use IP ranges for Public in Neutron

In v.3.2 IP address space for Public network is defined using CIDR.
Now it is defined through IP ranges and network mask.
Some network configuration checks are added/changed for Neutron.

Closes-Bug: #1247283

Change-Id: I455566455eed4333fb7bd8e74560692ef3e94003
Public IP range instead CIDR for Neutron (UI part) - 3.2.1

Change-Id: I56f03489caa464aa3f88b6d289719afb32d7e4d2