[agent] inspectValue refactor

Recognizes jQuery elements w/test.  Resolves https://github.com/marionettejs/marionette.inspector/issues/109
One perf update. I moved the `isKnownType` check from the top of `inspect()` into the array option as that's the only case for it.
Added an Agent IIFE and some code consistency updates.
mmm continue :)