Support api-version when building client
Support api-version when building client

Magnum service API is using micro versions and to get the correct
fuctions support, user or client have to initialize the correct
client with parameter 'api_version'. This patch is following the
same way as other OpenStack services to read the version from
OPENSTACK_API_VERSIONS of Horizon local_settings.py.

Change-Id: I85a3ed665dd6e5c9e9af933e0336d2be7998b928

openstack/magnum-ui,openstack/magnum-ui,openstack/magnum-ui,openstack/magnum-ui