reactive vlan_pop fix
-1 vlan now matches 'any vlan' in 0x04 backend
fix vlan hardcoding VInt16
Bug fixes to abstraction layer
added helper pretty printers for flowtable/flow/etc
Add logic to push vlan frames as needed when setting vlan
fold_left -> fold_right in from_seq
merge
Merge pull request #13 from frenetic-lang/fatkat

Fatkat