Add pagination and Changes-since filter support for os-migrations.

This patch adds pagination support and changes-since filter
for os-migrations API.

Users can now use 'limit' and 'marker' to perform paginate
query of running migrations list. Users can also filter the
results according to the migrations' updated time.

The ``GET /os-migrations`` and server migrations APIs will now
return a uuid value in addition to the migrations id in the response,
and the query parameter schema of the ``GET /os-migrations`` API no
longer allows additional properties.

Co-Authored-By: Yikun Jiang <yikunkero@gmail.com>

Implement: blueprint add-pagination-and-change-since-for-migration-list
Change-Id: I7e01f95d7173d9217f76e838b3ea71555151ef56

doc/api_samples/versions/versions-get-resp.json

@@ -22,7 +22,7 @@
                 }
             ],
             "status": "CURRENT",
-            "version": "2.58",
+            "version": "2.59",
             "min_version": "2.1",
             "updated": "2013-07-23T11:33:21Z"
         }