Ios pov support

[temahot]

Hey
I'd like to add
following code to NSTstreetViewManager.h for supporting bearing and others props in IOS

RCT_CUSTOM_VIEW_PROPERTY(pov, CLLocationDegrees, NSTStreetView) {
  if (json == nil) return;
   NSInteger tilt = [[json valueForKey:@"tilt"] floatValue];
   NSInteger bearing = [[json valueForKey:@"bearing"] floatValue];
   NSInteger zoom = [[json valueForKey:@"zoom"] floatValue];
   view.camera = [GMSPanoramaCamera cameraWithHeading:bearing pitch:tilt zoom:zoom];
}