Revert "Add AppData file"

This reverts commit 8bd17a357823f133f8e0208333e8a1151190f208.
appdata: Add skeleton appdata file

https://bugzilla.gnome.org/show_bug.cgi?id=722715
Finnish translation update
Finnish translation update
[l10n] Updated Catalan translation
[l10n] Updated Catalan (Valencian) translation
Version 3.13.90
Post release version bump
Updated Traditional Chinese translation(Hong Kong and Taiwan)
Updated Swedish translation
appdata: Add a simple description
Updated Assamese translation
Updated French translation
Updated Brazilian Portuguese translation
Updated Chinese (Taiwan) translation
Updated Galician translations
Updated Spanish translation
Updated Greek translation
Updated Indonesian translation
Updated gujarati translations