Fix: typeahead data storing in list items

Created by: re1ro

Unit test fails on typeahead with array of objects as source. When you use .attr('data-value') you can store only string there. To store objects you can use JSON.stringify or use $.data wich takes care of objects and it's shorter

For example I have

$.typeahead({
  source: [
    {firstName:'aa', lastName: 'oo'},
    {nickName: 'anon'}
  ]
})

And I want to search through all fields and do other magic. I can override matcher sorter highlighter updater. But it's gonna pass "[object Object]" into updater function.