Remove our broken IGMP snooping implementation.

  Our IGMP implementation (which has never really been tested) will not support multiple datapaths.
  Removing this feature, it can be added back when we have a real need for it.
Rework parsing engine. Adds full support for multi-dp.
 * Split off our old ugly parsing engine into a few classes
 * Adds back support for ACLs
 * Fixes installing broadcast flows for tagged/untagged ports
 * Clean ups
 * Bug fixes
Update distribution config file to show off new features.
Add support for ipv6 ACLs.
Add a readme.