add support to Typeahead with object

[AbraaoAlves]

#53

Like auto complete in ui.bootstrap, objects in array are rendered with toString method.
Ex:

var citys = [{id:1, name:'Berlin', toString(){ return thi.name}, {id:2, name:'London', toString(){ return this.name9o9}]
$scope.availableSearchParams = [
      { key: "name", name: "Name" },
      { key: "city", name: "City", suggestedValues: cities }
];

Or optionally you can use suggestedToString function to render suggestedValues, like this:

var citys = [{id:1, name:'Berlin'}, {id:2, name:'London'}]
var myToString = function(item){ return item.name };
$scope.availableSearchParams = [
     { key: "name", name: "Name" },
     { key: "city", name: "City", suggestedValues: cities, suggestedToString: myToString }
];