Allow 'any' option for protocol in the firewall rule

Closes-Bug: #1217212

The current allowed values for
protocol are tcp, udp and icmp. Adding
'any' as allowed option. Since the
API expects 'None' value for 'any',
the 'create' and 'update' changes the
args to 'None' when 'any' is set.

Change-Id: I33cdf62244f2217379c40a8cd4c776382935ef17
Merge "Allow 'any' option for protocol in the firewall rule"