Hints for font-viewer in main

Hints

• asv-nonstandard-gnome-extension
  :53 - 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-screenshot-media-url-not-secure
  :72 - http://raw.githubusercontent.com/FontManager/resources/master/font_viewer_main.png
  Consider using a secure (HTTPS) URL to reference this screenshot image or video.
• asv-screenshot-media-url-not-secure
  :77 - http://raw.githubusercontent.com/FontManager/resources/master/font_viewer_character_map.png
  Consider using a secure (HTTPS) URL to reference this screenshot image or video.
• asv-screenshot-media-url-not-secure
  :82 - http://raw.githubusercontent.com/FontManager/resources/master/font_viewer_properties.png
  Consider using a secure (HTTPS) URL to reference this screenshot image or video.
• asv-screenshot-media-url-not-secure
  :87 - http://raw.githubusercontent.com/FontManager/resources/master/font_viewer_license.png
  Consider using a secure (HTTPS) URL to reference this screenshot image or video.
• asv-url-not-secure
  :113 - http://fontmanager.github.io/
  Consider using a secure (HTTPS) URL for this web link.