Remove Map::start/stop

Both Android and iOS now use pause/resume. The map thread is
always running, and be able to receive messages. When paused,
it will just refuse to render.

android/java/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxgl/views/MapView.java

@@ -419,7 +419,6 @@ public class MapView extends SurfaceView {
 
         mNativeMapView.initializeDisplay();
         mNativeMapView.initializeContext();
-        mNativeMapView.start();
     }
 
     // Called when we need to save instance state
@@ -441,7 +440,6 @@ public class MapView extends SurfaceView {
     // Called when we need to clean up
     // Must be called from Activity onDestroy
     public void onDestroy() {
-        mNativeMapView.stop();
         mNativeMapView.terminateContext();
         mNativeMapView.terminateDisplay();
     }

android/java/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxgl/views/NativeMapView.java

@@ -73,14 +73,6 @@ class NativeMapView {
         nativeDestroySurface(mNativeMapViewPtr);
     }
 
-    public void start() {
-        nativeStart(mNativeMapViewPtr);
-    }
-
-    public void stop() {
-        nativeStop(mNativeMapViewPtr);
-    }
-
     public void pause() {
         nativePause(mNativeMapViewPtr);
     }
@@ -386,10 +378,6 @@ class NativeMapView {
 
     private native void nativeDestroySurface(long nativeMapViewPtr);
 
-    private native void nativeStart(long nativeMapViewPtr);
-
-    private native void nativeStop(long nativeMapViewPtr);
-
     private native void nativePause(long nativeMapViewPtr);
 
     private native void nativeResume(long nativeMapViewPtr);