Security Group rule validation for ICMP rules

Currently there is no validation in Security Group rules
when an ICMP rule is added with icmp code alone. A rule
is getting added but there is a mismatch between SG rules
and the corresponding iptables rule that is added.
This patch does the necessary validation on the input.

Closes-Bug: #1301838
Change-Id: I510abac4c426f68ea57c99a5fef3da4058f88797
Merge "Security Group rule validation for ICMP rules"