Update information provided by pulseaudio plugin to pulse.

The plugin now uses the generic name "OBS" to identify itself
to pulseaudio.

Until now the pulseaudio plugin used a placeholder icon for the
mixer to display. Now that we have a real icon installed to the
system we can use that instead.
Merge pull request #226 from fryshorts/pulse-input

Update information provided by pulseaudio plugin to pulse.