OVSDriver: make OFPP_LOCAL a first-class port

This enables sending packet-outs to OFPP_TABLE from OFPP_LOCAL.

Also clarified that port_desc_set takes a datapth port number, not an OpenFlow
port number.
OVSDriver: fix packet-out log message bug
OVSDriver: fix port lookup for OFPP_LOCAL
OVSDriver: fix CFR in_ports for reserved ports

aim_imin accepts signed integers, so large port numbers like OFPP_TABLE are
interpreted by it as small negative numbers.
OVSDriver: invert upcall userdata check

The IND_OVS_ACTION_CONTROLLER action translation uses the userdata to store the
packet-in reason.
OVSDriver: support OFPP_LOCAL as packet_in in_port
OVSDriver: translate between OVSP_LOCAL and OFPP_LOCAL in ind_ovs_key_to_cfr
ivs: make in_port 32 bits in the CFR
Merge into master from pull request #92:
improve support for OFPP_LOCAL (https://github.com/floodlight/ivs/pull/92)