reworked option id generation to be simpler, more consistent, and more
decoupled.
id's no longer depend on xml metadata and instead are generated via an
Underscore.js utility library. Ripped out all the "maxUsedOptionId"
stuff used in communicating with Reason. This actually makes the
dropdown/checkbox/radio option id stuff more of a candidate for
formbuilder proper (if we renamed it from reasonOptionId that is!)