Hints for gitg in main

Hints

• asv-nonstandard-gnome-extension
  org.gnome.gitg.appdata.xml:338 - 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-developer-name-tag-deprecated
  org.gnome.gitg.appdata.xml:673 -
  The toplevel `developer_name` element is deprecated. Please use the `name` element in a `developer` block instead.
• asv-developer-info-missing
  org.gnome.gitg.appdata.xml -
  This component contains no `developer` element with information about its author.