add missing header

src/MediaPlay.h

@@ -0,0 +1,11 @@
+/*
+ * Copyright 2017, Dario Casalinuovo. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+#ifndef _MEDIA_CLIENT_PLAY
+#define _MEDIA_CLIENT_PLAY
+
+int media_play(const char* uri);
+
+#endif