Fix droute test, and remove dbind dependency

Fix droute test, and remove dbind dependency

The droute test was broken (it had not been updated for recent API
changes and also did not return a non-zero exit code on failure). Also,
it is the only thing in at-spi2-atk that uses dbind, so re-worked it to
call libdbus directly, so that we can remove dbind / avoid having it
both here and in at-spi2-core.