MusicStateSpec: introduce new class describing the music state

Contains:
- state
- position
- playRate
- shuffle
- repeat

This is close to what PebbleProtocol currently supports.

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/MusicStateSpec.java

@@ -0,0 +1,12 @@
+package nodomain.freeyourgadget.gadgetbridge.model;
+
+/**
+ * Created by steffen on 07.06.16.
+ */
+public class MusicStateSpec {
+    public byte state;
+    public int position;
+    public int playRate;
+    public byte shuffle;
+    public byte repeat;
+}