Removed "the" from MPRIS commands

It was slightly awkward to say, and probably didn't help recognition
any.

kayleevc/plugins/mpris.py

@@ -38,10 +38,10 @@ class Plugin(PluginBase):
         self.commands = {
             'next song': self._next,
             'next video': self._next,
-            'pause the music': self._pause,
-            'pause the video': self._pause,
-            'play the music': self._play,
-            'play the video': self._play,
+            'pause music': self._pause,
+            'pause video': self._pause,
+            'play music': self._play,
+            'play video': self._play,
             'previous song': self._previous,
             'previous video': self._previous
         }