Use existing styles for table in tasktemplate view.
Merge pull request #388 from 4teamwork/jin-tasktemplate-markup

Use existing styles for table in tasktemplate view.
Fix xlsx convert script to correctly write integer values.
CSV source is typeless. So we read everything as string. But the xlsx has to be written with the correct type.
Ergo a mapping which column is different from string is required.
Merge pull request #391 from 4teamwork/lk_fix_xlsx_convert_script

Fix xlsx convert script to correctly write integer values.
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.