Incremental cleanup / perf improvements

I've changed a few things here:

* Cleaning up the cleanup extensions to not have a "global" variable
* Use direct DOM access instead of jQuery because it's faster -- I plan to do more of this
* It's confusing to have both `$element` and `$el` -- I'm replacing the first with `_container` -- this is in progress
* Redoing the outerValue/value checks
** The handleUnsanctionedTags caused issues in Android because of needing to saveSelection. And it's faster in general to first check if there are unsanctioned tags and only saveSelection if there are.
** Also, the whole caching of the value and outerValue was weird, and it's now back to only firing onvaluechange if the value actually changes, not if the outerValue changes too
** Removing oldValue from the onvaluechange event -- if the consumer cares about that they can save it themselves

* Modify gruntfile so that you can specify what plugins to build
** e.g. `grunt build  plugins=InsertCommand,keyboardHandler`