rflib: Introduce TLV, Match, Action Types for Python

New TLV, Match and Action structures can be used to manipulate
the binary values of matches and actions in human readable forms.
rfserver: Add support for RouteMod structure

When RFClient sends a RouteMod, RFServer will replace the DPID/Port and
forward to RFProxy. Behaviour of RouteInfo->FlowMod messages remains
the same.
rfclient: Replaces RouteInfo with RouteMod