Fix handling of CIDR in allowed address pairs

A CIDR in allowed address pairs would screw up
the calculation of remote security group member
IP addresses due to a call that assumed each entry
was an IP. This patch fixes that an adds a remote
security group reference to the address pairs SG
test case to exercise this code-path.

Closes-Bug: #1382562
Change-Id: I2676f4b56bce7449579d67fb221b3edb7b885103
(cherry picked from commit a1e78b2e8836053d8ffb29bce0f862e8a5f19c2f)
Merge "Fix handling of CIDR in allowed address pairs" into stable/juno