RemoteViewsTarget feature requested on #242

Ability to load a bitmap into an ImageView of a Widget using
RemoteViews.

Example of usage on the following gist
https://gist.github.com/pavlospt/00242d5102ac8f76e169
`int...` varargs would be nicer in case there's only on widget target, less code on client side. Also isn't this NonNull as well?