Index mappings not preserved in backups

Problem

1. Elasticsearch indices have their nice mappings.
2. We only backup index data, we ignore the mapping.
3. When we restore the index data, some implicit mapping is created.
4. That mapping may not be necessarily correct.
5. Problem.

Solution

1. elasticsearch-dump can dump/restore mappings.
2. We should do that.
3. Maybe we should also do the same with other dump types: settings, analyzer, alias.