Implement simple schema/index management mechanisms in UI
- Show index size
- Show if outdated mapping
- Clear index
- Rebuild index
- Crawl offline/online
(from redmine: issue id 512, created on 2018-01-22tgradl, closed on 2018-01-24)
(from redmine: issue id 512, created on 2018-01-22tgradl, closed on 2018-01-24)