[PRD-2455] Add more checks to check_networks task

Following checks are implemented now for Nova-Network:

1) +  VLANs of all networks shouldn't be intersected to each other (all network modes) or Fixed VLAN range (VLAN manager).
2) +  IP address spaces of all networks in cluster shouldn't be intersected to each other (exception: Floating ranges can be in Public CIDR).
3) +  IP address ranges inside Public and Floating networks shouldn't be intersected to each other.
4) +  Public ranges should be in one CIDR which calculated by netmask.
5) +  Public network should have a gateway field and it should belong to Public CIDR but should not be in any Public or Floating range.
6) +- Public and Floating networks are rated as a single network when they assigned to nodes' physical interfaces.
      So they must share one VLAN and must be assigned together to one interface.
7) +  Any physical interface of any node can have one assigned untagged network only (exception: point 6).
8)  - All networks should belong to the allowed IP ranges (network of class A, B or C excluding loopback range).
9) +  VLAN IDs shouldn't be out of range 2, 4094. Untagged network should have VLAN ID == None.
10) - Number of Fixed networks should fit in Fixed CIDR and size of one Fixed network.

Some error messages are refined and unified.

Change-Id: Ieb4c1666112d8acb0c7413e8c6b09271119703f3
Merge "[PRD-2455] Add more checks to check_networks task"