The height of the dialog increased due to the recently added additional
fields for certificate selection and identities. On some screens the
fields to configure custom proposals were not visible anymore.
Together with less spacing on the top level GtkBox this change reduces
the height by about 80 pixels.
Fixes#3448.
The path '/usr/share/appdata' is deprecated as is the .appdata.xml
extension, files should be in installed in '/usr/share/metainfo' with
a .metainfo.xml extension.
According to the docs, the metainfo path should be well supported even
by older distros like Ubuntu 16.04.
Reference: 2.1.2. Filesystem locations
https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html
This will ensure the strongSwan NetworkManager plugin will be easily
installable from the app stores such as GNOME Software.
Closesstrongswan/strongswan#41.