Hints for deja-dup in main

Hints

• asv-nonstandard-gnome-extension
  org.gnome.DejaDup.appdata.xml:341 - kudos
  This tag is a GNOME-specific extension to AppStream and not part of the official specification. Do not expect it to work in all implementations and in all software centers.
• asv-content-rating-missing
  org.gnome.DejaDup.appdata.xml -
  This component has no `content_rating` tag to provide age rating information. You can generate the tag data online by answering a few questions at https://hughsie.github.io/oars/