Add support for protocol numbers

This patch adds support for passing in protocol numbers into the API.
For example, 1 instead of ICMP. This allows all protocols besides
just TCP/UDP/ICMP to be used. This patch includes changes to support
this for the NVP Plugin. Existing plugins using securitygroups_rpc_base
and OVSHybridIptablesFirewallDriver require no change to leverage this.

Implements blueprint security-group-rules-protocol-numbers

Change-Id: I7d3b6986d9d0dadbefac0ea7798475a573dac046
Merge "Add support for protocol numbers"