Add negative tests for snapshot pagination

Added negative tests:
- snapshot list by invalid 'sort' param
- snapshot list by invalid 'marker' param
- snapshot list by invalid 'limit' param

Note: There is a bug related to 'name', 'status' and 'volume_id' parameters,
since, inserting invalid value for those parameters returns an empty list.

Change-Id: Ieeb81c69458b4b3028a929096d0f121e34111edc
2 files changed