packet_to_flow_match: use OFPVID_PRESENT

The spec requires OFPVID_PRESENT (the CFI bit) to be included in the vlan_vid
value if matching on a vlan id.
nicira_dec_ttl: fix syntax error
nicira_dec_ttl: add TtlDecrementZeroTtl
tests-1.3: add actions test module

These tests check the behavior of each type of action. The matches used are
exact-match, to satisfy the OXM prerequisites of the set-field actions.
These tests use a single apply-actions instruction.

Only a few action tests have been implemented: push vlan, pop vlan, set vlan
vid/pcp.
update pyloxi to c47bc6facb2869a7833b8694b7a20b3113284d94
testutils: add openflow_ports()

This function replaces the common boilerplate code that gets a list of port
numbers from the config dictionary and checks that enough ports are available
for the test.

I changed the OF 1.3 tests to use this function.
Merge pull request #60 from rlane/actions

initial OF 1.3 actions tests