Code review comment for lp:~mandel/ubuntuone-dev-tools/use_correct_reactor

This is a bit backwards from what is being done in the ubuntuone projects, where dbus is getting used on non-Windows platforms. There will also have to be more work to be able to do this, as tests that use the DBus runner are going to require the glib reactor for doing async calls. So I guess we also need to have some way to check that the reactor and service runners are compatible in some way, otherwise you will get lots of weird errors running the tests on something other than Linux.