Multimedia keys are not properly supported

The support for multimedia keys in Yocto is implemented by watching for MediaPlayerKeyPressed messages in the output of dbus-monitor. This is incorrect and the media key support should be implemented in the same way as in Rhythmbox (See http://google.com/codesearch/p?hl=en#jPEBwuiOcHQ/plugins/mmkeys/rb-mmkeys-plugin.c ). In particular, Yocto should use a native DBus implementation, and should call GrabMediaPlayerKeys and ReleaseMediaPlayerKeys to avoid conflicts with other programs (such as Evince).