OVSDriver: fix features reply for OF 1.3

The ports and actions are no longer included in the features reply. The
OpenFlow version is taken from the reply object.
OVSDriver: fix table stats for OF 1.3
OVSDriver: fix packet-in for OF 1.3
OVSDriver: use correct OpenFlow version for various reply messages
ivs: add command line argument to set the OpenFlow version
Merge into master from pull request #28:
Improve OF 1.3 support (https://github.com/floodlight/ivs/pull/28)