VPNaaS support for VPN service admin state change and reporting

For VPN service admin state changes, hook up the API call to the service
driver so that the configuration changes can be applied.

Modify the status reporting, so that the VPN service and IPSec
connection status' match the actual status when admin state down
actions are performed (on both the service and connection).

Change-Id: Ife7176675d20bb3ea529a4d79fa92a61f9550a6a
Closes-Bug: 1291609
Correct OVS VXLAN version check

Update the version checking logic used to determine if the combination of
Linux kernel, OVS userspace, and OVS kernel module can properly support
VXLAN.

Tested on Ubuntu 14.04 without the OVS DKMS module.

Closes-Bug: #1291535

Change-Id: If034164b775989d52c3c449caba6baadb970afd9
Import request_id middleware bug fix from oslo

There is a bug in request-id middleware that a subsequent API request will
overwrite a request-id of a previous request when multiple API calls are
processed in parallel in request_id middleware.
This commit imports the fix in oslo.

cherry-picked from oslo-incubator d7bd9dc37ac3d6bc171cd2e290c772633ad20a32
Closes-Bug: #1289696
----
Don't store the request ID value in middleware as class variable

The original version of the request_id middleware generates a request ID during
process_request() and stores the value in a variable, so it can be attached as
header in process_request(). This is pretty dangerous, since subsequent
requests will overwrite this value, and the wrong request ID may be attached to
some responses. This is particularly apparent when requests arrive in parallel.

This change replaces process_request() and process_response() with an override
of __call__(). This allows the generated req_id to be used in the response
header without needing to save it as a class-level variable.
----

Change-Id: Ic20047f604394f1ce4900c3b6a00595223804cba
nec plugin: allow to delete resource with ERROR status

Previously if a resource is in ERROR status and there is no
corresponding resource on OpenFlow controller, the resource
cannot be deleted through an API request.
This commit rearrange ERROR status check to allow resource
with ERROR status to be deleted.

Closes-Bug: #1295754
Change-Id: I709f5e2066eb5d12ec0f42dff15797acddc2009e
Merge "Import request_id middleware bug fix from oslo"
Merge "Correct OVS VXLAN version check"
Merge "VPNaaS support for VPN service admin state change and reporting"
Merge "nec plugin: allow to delete resource with ERROR status"