fix class not being added to div for response
rename selectonequestion.js to multiplechoicequestion.js
rename the widget to match the renamed file: MultipleChoiceQuestion

Also some other minor tweaks, comment updates.
Finish up changes to SubmitManager

added missing comments
also got the unit tests back to failing for a reason leslie can address, or more likely we all (seann, me and leslie should discuss what is the expected behavior of the submit manager).
Merge pull request #61 from mlippert/widget-refactor

renamed multiple choice widget