[web] don't link to None in author box (when author has been deleted) (closes #2409855)

dbapi: try to restore compatibility of the connect api with 3.15 A few issues here: - urlparse('foo').scheme is '', not None - cnxprops is an optional argument Regression from 62213a34726e ("[db-api/configuration] simplify db-api and configuration so that all the connection information is in the repository url, closes #2521848") Closes #2754322

3.16 is the new stable After discussion with David Douard I'm merging 3.16.x branches in stable and starting 3.17 feature on default.