OVSDriver: bring vlan bits in the cfr closer to OpenFlow 1.3

OpenFlow 1.3 includes the CFI bit, indicating a tag is present, in the vlan_vid
field. This change reverses the previous meaning of the CFI bit (which
indicated untagged) in the CFR to simplify translating a 1.3 match into a CFR
(in the next commit).
OVSDriver: translate OF 1.3 vlan match

The vlan_vid match field in OF 1.3 includes the CFI bit, which if set matches a
valid VLAN tag.
Merge into master from pull request #30:
OpenFlow 1.3 VLAN matching (https://github.com/floodlight/ivs/pull/30)