GetVersion() was introduced in FAB-2960 and requires additional unit tests.

Tests were added to verify retrieval by namespace and key.

Negative test added to test for response for non-existent namespace and key.

Change-Id: Ia2aa96b63cc62a5d97e672375fe13de948ca5305
Signed-off-by: Chris Elder <chris.elder@us.ibm.com>