Add a js-enhanced multi-select
Add html and validation for refactored multi-select

- js and css to support multiselect rewriting
- html template addition for reworked mutli-select
- validation methods updated to match the POST data sent by the
  reworked field
travis modification
Updated tests to validate last three commits

- updated tests for meta box validation specifically around changes
  to the validation routine
remove erroneous enqueue_style at line 43
Fixes a typo at meta-box-models#L188
Merge pull request #6 from gboone/master

New form field for `multiselect` and tests to validate