refactor(workspace): Use new API from DocManager (refs #4705)

Remaining problems:
- The search field does not work as the filter is not applied when a collection
  is used (so all documents are returned).
- Clicking on the trash generates an error as the setOrder("title desc") does
  not work when the collection is a MSEARCH.
Merge pull request #15 from eguaj/1.2-A4705

refactor(workspace): Use new API from DocManager (closes #4705)