Add test to API Version object
Add test to API Version object

At this time, API Version object is not fully tested,

* __init__ method is not tested.
* __repl__ method is not tested.
* parse_headers method is not tested.

This patch adds these tests.

Change-Id: I5a1f02146681b68a5d77b5b50f7907999a6bb263
Closes-Bug: #1464441

ffantast/magnum,LaynePeng/magnum,Tennyson53/SUR,ArchiFleKs/magnum,eshijia/SUR,mjbrewer/testindex,hongbin/magnum,mjbrewer/testindex,Tennyson53/magnum,Tennyson53/SUR,eshijia/SUR,sajuptpm/magnum,jay-lau/magnum,hongbin/magnum,Alzon/SUR,sajuptpm/magnum,Tennyson53/magnum,annegentle/magnum,eshijia/magnum,ArchiFleKs/magnum,ddepaoli3/magnum,ChengTiesheng/magnum,dimtruck/magnum,paulczar/magnum,openstack/magnum,Alzon/SUR,annegentle/magnum,ffantast/magnum,dimtruck/magnum,eshijia/magnum,openstack/magnum,ramielrowe/magnum,paulczar/magnum,ddepaoli3/magnum,ChengTiesheng/magnum,LaynePeng/magnum,mjbrewer/testindex,ramielrowe/magnum