Support for custom collections
- add other collections with different schemas as proof of concept
- prepare extraction such as tei
(from redmine: issue id 70, created on 2018-01-22tgradl, closed on 2018-01-22)
- add other collections with different schemas as proof of concept
(from redmine: issue id 70, created on 2018-01-22tgradl, closed on 2018-01-22)