Unskip test_snapshot_list_param_limit_equals_zero

test_snapshot_list_param_limit_equals_zero was skipped because
of #1540893 There was a bug in Cinder v1 and v2 (only in Kilo
release) when list snapshot was called with a limit of 0.

Now that all supported branches have the fix in Cinder, we can
unskip the test.

Change-Id: Ia2ba9c9ee99b8ae3d1b82e98a0810b2185f34c45
Related-Bug: #1540893
1 file changed