Fixed crash when using camera since options was defaulted to null since it wasn't passed through.

This fixes a crash for source type of camera since if you don't pass options through it will crash when it tries to reference the property options.DefaultCamera

e.g. 
-      var picker = SetupController (ndelegate, sourceType, mediaType);
+      var picker = SetupController (ndelegate, sourceType, mediaType, options);

And then in SetupController would crash on the second line below:
if (sourceType == UIImagePickerControllerSourceType.Camera) {
				picker.CameraDevice = GetUICameraDevice (options.DefaultCamera);