rfserver: Replace DatapathConfig with RouteMod

 - Create matches and actions for DatapathConfig at the server rather
   than the proxy, reducing complexity at the proxy side.
squash! rfclient: Replaces RouteInfo with RouteMod

Bugfix: ipdst Match pointer running out of scope
squash! rflib: Introduce TLV, Match, Action Types for Python

Bugfix: Pad integers to appropriate length when dealing with binary form
squash! rfserver: Replace DatapathConfig with RouteMod

Bugfix: Misc fatal DatapathConfig->RouteMod related bugs in rfserver
squash! rflib: Introduce TLV, Match, Action Types for Python

Added default netmask for creating an IPv4 Match - 255.255.255.255
squash! rfserver: Add support for RouteMod structure

Minor bugfix: Consistent naming - vmid -> vm_id