fix cleanup of selectgroup test

as it was copied from radiogroup test before that got fixed it had the same issue leaving the test div behind.
initializing eventmanager in init, not in the getter method
Merge pull request #51 from seannives/seann

initializing eventmanager in init, not in the getter method
refactor button widget to have draw method

this breaks all pages which use buttons. I've updated the button test page, but there are more.
Merge pull request #52 from mlippert/widget-refactor

Button widget refactor to use draw