Hints for meld in main

Hints

• asv-nonstandard-gnome-extension
  :167 - 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-url-not-secure
  :188 - http://www.gnome.org/friends/
  Consider using a secure (HTTPS) URL for this web link.
• asv-desktop-app-launchable-omitted
  -
  This `desktop-application` component has no `desktop-id` launchable tag, however it contains all the necessary information to display the application. The omission of the launchable entry means that this application can not be launched directly from installers or software centers. If this is intended, this information can be ignored, otherwise it is strongly recommended to add a launchable tag as well.