Avoid processing ports which are not yet ready

This patch changes get_vif_port_set in order to not return
OVS ports for which the ofport is not yet assigned, thus avoiding
a regex match failure in get_vif_port_by_id.
Because of this failure, treat_vif_port is unable to wire
the port.
As get_vif_port_by_id is also used elsewhere in the agent, it has
been enhanced in order to tolerate situations in which ofport might
have not yet been assigned.

The ofport field is added to the list of those monitored by the
SimpleInterfaceMonitor. This will guarantee an event is generated
when the ofport is assigned to a port. Otherwise there is a risk
a port would be never processed if it was not yet ready the first
time is was detected. This change won't trigger any extra processing
on the agent side.

Finally, this patch avoids fetching device details from the plugin
for ports which have disappeared from the OVS bridge. This is a
little optimization which might be beneficial for short lived ports.

Change-Id: Icf7f0c7d6fe5239a358567cc9dc9db8ec11c15be
Partial-Bug: #1253896
Remove DEBUG:....nsx_cluster:Attribute is empty or null

They serve no purpose, as if an important attribute is empty
or null and it shouldn't we'll know about it, and that's what
counts.

Change-Id: I7783cb6df76362d1b9b25b23f89a3a5d6df15406
Closes-bug: 1280500
Merge "Avoid processing ports which are not yet ready"
Skip a test for nicira service plugin

test_router_add_interface_subnet_with_port_from_other_tenant
is causing intermittent failures in unit tests because of
issues related with sql session autoflush.

This patch skips this test, since it is already covered
by another test case in the same module. This should prevent
job failures while the relevant bug is addressed.

Change-Id: Iad33dada61d17fad14e569e241f4079465b5f792
Related-Bug: 1280035
Imported Translations from Transifex

Change-Id: Id68ff4a10fa3aa0bfdbc128723a9e0e47f3d93b3
Merge "Remove DEBUG:....nsx_cluster:Attribute is empty or null"
Merge "Skip a test for nicira service plugin"