basic netcore support for tracking policy evaluation
option parsing for pyretic.py, including mode option
minor pass on topology detection code
fixed network/topology equality testing
improved topology-aware policies
should have been in aee018b0543f72450c5a65781caa515e7351437f
Policies that notify runtime when they change.
mac_learner now resets behavior when network topology changes.
Streamlined data serialization between backend and of_client
Refactor fixed header lists
Method to send all packets to controller
VLAN zero reserved, will not be used for tagging
Basic reactive rule installation
Minor improvement to mode options