pipeline: move in logic from forwarding

The internal OVSDriver header is required by the pipeline code. This will be
cleaned up in a later commit in this pull request.
pipeline: factor out flowtable lookup

The pipeline gets a function pointer to use when it wants to lookup in a table.
pipeline: pass in openflow version to create
pipeline: take CFR as input
pipeline: move and rename ind_ovs_fwd_result
pipeline: change stats ptr array to an xbuf

This allows it to grow arbitrarily.
add skeleton ivs module
ivs: move common definitions to new ivs module