Added answerKey definition to activity schema

This version has an answerKey-multiplechoice schema w/ 2 possible "answers" property definitions, one which is an object where the properties of the object are to be the choice key, and one which is an array where the choice key is a property of the object stored in the array.
Add Legend getEventTopic static method
Make BricWorks pass itself as the 3rd argument to bric constructors

This will be needed by bric's which create other brics, particularly when the bric type is specified in the config such as for the choice presenter that multiplechoice uses.
Add BarChart getEventTopic static method
Changed mc config to use BricTypes instead of a constructor function

renamed the config properties
removed "svgBric" support, which should not be done the way it was.
Instead renamed the old MultipleChoiceQuestion bric to MultipleChoiceQuestionOld so the prototype pages using it will still work.
Restore old MultipleChoiceQuestion bric as MultipleChoiceQuestionOld for use by prototype pages that use an svg bric for the choice presenter

Change the 2 demo pages to use this Old bric
Fix various syntax errors and such in the ManzaHealth.html demo so that it works again

Uses the new MultipleChoiceQuestion config