servers list API support specify multi-status

Currently the service list API allows the user to specify an optional status
value to use as a filter - for example to limit the list to only servers with
a status of Active.

However often the user wants to filter the list by a set of status values,
for example list servers with a status of Active or Error,
which requires two separate API calls.

Allowing the API to accept a list of status values would reduce this to a
single API call.
Allow to specify status value for many times in a request.
For example::
    GET /v2/{tenant_id}/servers?status=ACTIVE&status=ERROR
    GET /v3/servers?status=ACTIVE&status=ERROR
V2 API extension::
    {
        "alias": "os-server-list-multi-status",
        "description": "Allow to filter the
            servers by a set of status values.",
        "links": [],
        "name": "ServerListMultiStatus",
        "namespace": "http://docs.openstack.org/compute/ext/
            os-server-list-multi-status/api/v2",
        "updated": "2014-05-11T00:00:00Z"
    }

DocImpact: Adds os-server-list-multi-status extension.

blueprint servers-list-support-multi-status

Change-Id: Id0109c56070e2f920be0f95738749aa969258bc1
Merge "servers list API support specify multi-status"