Previously we unconditionally skipped a large amount of code for no
reason unless the updates required a system restart.

This was done the same in GNOME Software, so it's nice to have for
consistency.

For GNOME Software, major distributions like Fedora, Debian and Ubuntu
enable this by default anyway and all the old bugs that prevented this
from being on-by-default seem to have been resolved.
Distributions where this is not the case can always override the setting
to change the default back again.

Resolves: #5

Improve changelog display

See merge request !7

We just render the changelog verbatim as monospaced text now, instead of
failing and displaying no update information at all.