Simplify is_available() method of osx-speaker

Author: Holzhaus

Diff for: client/speaker.py

@@ -118,7 +118,7 @@ class saySpeaker(AbstractSpeaker):
 
     @classmethod
     def is_available(cls):
-        return (super(saySpeaker, cls).is_available() and subprocess.call(['which','say']) == 0)
+        return (platform.system() == 'darwin')
 
     def say(self, phrase):
         cmd = ['say', str(phrase)]