Button Re-write

This replaces PR #1216 

This includes new widget controlgroup which replaces buttonset
Current known issues 
 - [x] Checkboxradio testfailure missing default element (@scott_gonzalez said it should not have one because it cant be sane ) this causes common tests to fail
 - [ ] Backcompat
 - [x] Controlgroup icon only buttons 1px too short in chrome, firefox extra weird @jaspermdegroot think you could take a look?
 - [x] demos/controlgroup/default.html As above, labels should demo something
 - [x] demos/checkboxradio/default.html doesn't have the "command line" anymore, but still doesn't look like a demo. Labels should reflect some real world usecase.
 - [ ] demos/button/icons.html still looks like a visual test, not a demo

The space at the beginning in the string isn't necessary. The "ui-icon" class probably shouldn't be here it, just as it is missing in the same variable in button.js. Its only added to the icon span, so there's no need to remove it later.