title: Android map v2 zoom to show all the markers
body: <p>I have 10 markers in the <code>GoogleMap</code>. I want to zoom in as much as possible and keep all markers in view? In the earlier version this can be achieved from <code>zoomToSpan()</code> but in v2 I have no idea how about doing that. Further, I know the radius of the circle that needs to be visible.</p>