Proper validation for inserting firewall rule

Say rule r2 is associated with policy p2. If user tries to insert rule r1
into a policy p1 before/after r2, error should be thrown saying that rule
r2 is not associated with policy p1.

Change-Id: Ifa415acc9533b7a323f966ee42d476460e68c9d3
Closes-bug: 1330898
Merge "Proper validation for inserting firewall rule"