subprocess.call() —> call() to avoid NameError

```
>>> from subprocess import call
>>> call('ls')  # this works
>>> subprocess.call('ls')  # but this raises a NameError because subprocess was not installed
Traceback (most recent call last):
  File "<string>", line 1, in <module>
NameError: name 'subprocess' is not defined
```

cmus-osx/media-keys.py

@@ -26,19 +26,19 @@ def sendEvent_(self, event):
 		if key_repeat and key_state is not NSKeyUp:
 			if key_code == 20:
 				self.repeated = True
-				subprocess.call(['cmus-remote', '-k', '-10'])
+				call(['cmus-remote', '-k', '-10'])
 			elif key_code == 19:
 				self.repeated = True
-				subprocess.call(['cmus-remote', '-k', '+10'])
+				call(['cmus-remote', '-k', '+10'])
 
 		if key_state is NSKeyUp:
 			if self.repeated:
 				self.repeated = False
-		elif key_code == 20 or key_code == 18:
+		elif key_code in (20, 18):
 			call(['cmus-remote', '-r'])
 		elif key_code == 16:
 			call(['cmus-remote', '-u'])
-		elif key_code == 19 or key_code == 17:
+		elif key_code in (19, 17):
 			call(['cmus-remote', '-n'])
 
 
@@ -81,4 +81,4 @@ def get_cmus_instances():
 	single_instance_checker.start()
 	AppHelper.runEventLoop()
 else:
-	exit(1)
+	exit(1)