Imports optimization and entries rearranged

app/src/main/java/com/cappielloantonio/play/interfaces/Playback.java

@@ -23,14 +23,14 @@ public interface Playback {
 
     int getProgress();
 
-    int getDuration();
-
     void setProgress(int progress);
 
-    void setVolume(int volume);
+    int getDuration();
 
     int getVolume();
 
+    void setVolume(int volume);
+
     interface PlaybackCallbacks {
         void onStateChanged(int state);