Refactor matching functions in linc_us4_routing

These functions didn't have enough descriptive name and thus were
poorly readable.
(Motivated by #134).
Add support for matching VLAN tagged packets

So far LINC has tried incorrectly match on VLAN tagged frames.
It hasn't taken into account that OFPXMT_OFB_VLAN_VID field has
an additional bit to indicate special conditions regarding VLAN tags.
Now LINC support all possible matches on VLAN tagged frames.
(Motivated by #134).
Add controller's scenario verifying matching on masked VLAN tag

This scenario checks if the switch correctly interprets flow modification
message indicating matching on masked VLAN tag.
(Motivated by #134).
Merge pull request #198 from FlowForwarding/issue134

Fix matching on VLAN tagged frames