OVSDriver: support very limited OF 1.3 instructions

Only supports a single apply-actions instruction.
OVSDriver: remove assertion on of_match_t version

The code will work for a subset of OF 1.1+ matching. As long as the packet is
IPv4/TCP it should work fine.
Merge into master from pull request #27:
Limited OF 1.3 forwarding support (https://github.com/floodlight/ivs/pull/27)