Properly dispose of sdlManager in onDestroy

Author: RHenigan

hello_sdl_java/src/main/java/com/smartdevicelink/java/SdlService.java

@@ -130,6 +130,7 @@ public void onDestroy(SdlManager sdlManager) {
                     SdlService.this.sdlManager = null;
                     if(SdlService.this.callback != null){
                         SdlService.this.callback.onEnd();
+                        stop();
                     }
                 }