RM7213 Added IPPolicyCIDR.{first_ip, last_ip}

* Tested against production dbs.
* There was a bug in master when comparing it to the changes I had made, thus 2 commits instead of one (I had got the boolean sign wrong for allocated IPs). 

The integer I'm assuming is the last ip in the policy? Could we get this integer from netaddr instead of having it magically be there? At least defined in the __init__ or setup as a shared constant.