Some gitlab updates (SWAG-522)

Fixed the following gitlab issues:
- disable "delete old branch" checkbox when merging FROM protected branch
- allow filters on merge request page to work together, not just one at a time
- fix CSS for accept/reject/etc buttons on merge request detail page to be on the same line

Jira task - https://prodegellc.atlassian.net/browse/SWAG-522 (Gitlab updates)