Version bump 1.6
Version bump 1.6

* Fix SetContext activity
* Add new workflow items for export/download workflows
* Add new API method is_certificate_owner
* Fixes to set_motd and csr workflow (cosmetic)
* Improve display for download links in UI

oliwel/openxpki,aleibl/openxpki,oliwel/openxpki,stefanomarty/openxpki,stefanomarty/openxpki,openxpki/openxpki,oliwel/openxpki,aleibl/openxpki,oliwel/openxpki,stefanomarty/openxpki,stefanomarty/openxpki,openxpki/openxpki,aleibl/openxpki,stefanomarty/openxpki,stefanomarty/openxpki,aleibl/openxpki,aleibl/openxpki,openxpki/openxpki,openxpki/openxpki,aleibl/openxpki,oliwel/openxpki,oliwel/openxpki