Migrated to qtdbus. Thanks to mgoral :
DBusInterface has been almost completely rewritten. Now, instead of
checking for DBus messges every
period of time, it uses signal-slots mechanism to listen and react on
demand. Code is also a lot
simplier: instead of sending low level DBus messages, reply parameters
are simply passed back by
reference.

DBusInterface is now separated from Widget. It's now required to call
connectToDBus(DBusInterface&)
to connect both.  This is a first step to provide a separate interface
for DBus Message listeners.

Because QtDbus is now used instead of libdbus-1-dev, it's removed from
dependency list and is not
compiled anymore.