Fix the experimental SC.SelectView to display the icon of the selected item
Fix SC.SelectView tests
Fix SC.SelectView test: menu_resing.js

The test will pass when my other pull request
https://github.com/sproutcore/sproutcore/pull/947/files will be
submitted.
Add the defaultIcon property and some tests for it
Merge branch 'select-icon' of https://github.com/nicolasbadia/sproutcore into mirion_dev/select_view_exp