Fixed issue #9 (added multi_select field type).
Fixed issue #12 (added support for chosen.js).
Changes as requested by @jkudish; updated chosen.js to current version.
Relocated chosen.js version definition.
Merge pull request #28 from greatislander/master

Add support for multi-select field with optional support for chosen.js. Fixes #9 and ref #12.

props @greatislander