Cloud Formation overload "ports" parameters for icmp protocol

[vchepkov]

cfn_nags generates W27 warning for a code fragment:

    SecurityGroupIngress:
        - Description: Allow ICMP ping
          IpProtocol: icmp
          FromPort: 8
          ToPort: 0
          CidrIp: "10.0.0.0/8"

Cloud Formation repurposed ports attributes as "type and code" for icmp protocol, so the warning about port ranges should be suppressed