Enhanched 'typeahead' binding

This way you can use a typeaheadOptions binding to pass any typeahead specific option. i.e. data-bind="typeahead: fooValuesArray, typeaheadOptions: { items: 15, minLength: 3, updater: function(item) { return item; } }"
Merge pull request #44 from flinco/master

Enhanched 'typeahead' binding