Fix opengever.base metadata version to match upgrade-step.
Merge pull request #394 from 4teamwork/lk_fix_opengever.base_metadata_version

Update metadata version of `opengever.base`
Reworked OpengeverNavtreeStrategy to fix document-icons in contenttree widget.
Merge pull request #390 from 4teamwork/pg_navtree_fix

Display document-icons in ContentTreeWidget
Fix indentation, use 4 spaces.
Force display of edit-bar when pdf-task-report is available.
Move pdf-task-report action to actions menu.

Fixes #383 (menu assignment only), Fixes #322.
Merge pull request #399 from 4teamwork/deif-pdf-task-report-action

Move pdf-task-report action to action menu.
Added download copy in tooltip.

Fixed mock tests.
Initialized opengever.sharing version. Moved prepoverlay initialization to opengever.base.