Move standard OpenFlow forwarding to pipeline_standard

Reviewer: @harshsin

IVS has long supported pluggable forwarding pipelines, but the default OpenFlow
1.0/1.3 code was still in OVSDriver. This change moves most of it to
pipeline_standard. The remaining bits are match and action translation.

Along with deleting the moved code from OVSDriver, I also deleted a bunch of unused features.

I plan to move the CFR and action translation to pipeline_standard in a future pull request. Action translation in particular is more involved because it's also used by packet-out.