[WIP] Make Chosen framework agnostic using native JS

This PR takes over previous efforts to make Chosen framework-agnostic:

* [Daniel Lo Nigro](https://github.com/harvesthq/chosen/pull/1394)
* [Arnaud Ceccaldi](https://github.com/harvesthq/chosen/pull/1727)

This native version is now up-to-date with `master` as of January 23rd, 2014.