BamfView: reload the view children everytime it changes dbus path
Without doing it we could have children-less views in case we have just
re-matched a view with a different dbus path (this happens in general
for desktop-less applications), because the proxy won't be fast enough
to catch the signal to update the inner children list. Fixes: https://bugs.launchpad.net/bugs/1238064.
Approved by Christopher Townsend, PS Jenkins bot.