new function selectizeInput() to use selectize.js
roxygenize
add updateSelectizeInput() accordingly
the search field must be renamed accordingly
news for selectizeInput()
factor out the code to determine which options should be evaluated into a utility function checkAsIs(), so that it can be applied to selectizeInput() as well
apply checkAsIs() to selectizeInput(), and store the names in data-eval in the script

note we switched the order of {} and config.text() in $.extend(), so that users can overwrite the default options like labelField, valueField, ...
it is safer to evaluate the string inside ()

e.g. one cannot directly evaluate {a: 1, b: 2}, although it is legitimate JSON; eval("({a: 1, b: 2})") always works
add a note about the I() options in selectizeInput()
add es5-shim.js for IE8