Makes the experimental SC.SelectView fully backward compatible with the legacy one.

This pull request adds the missing features of the legacy `SC.SelectView` to the experimental one.
The experimental `SC.SelectView` makes use of SC.MenuPane to render the menu. It also include `SC.AutoResizingMenuPane` which add support for automatic resizing.
I've includes the unit tests of the legacy one to prove the backward compatibility.

This PR includes the following fixes: https://github.com/sproutcore/sproutcore/pull/965 https://github.com/sproutcore/sproutcore/pull/947 https://github.com/sproutcore/sproutcore/pull/957