Add support for IN and !IN queries

var db = new TAFFY([
	{id:1, title:'Test1'},
	{id:2, title:'Test2'},
	{id:3, title:'Test3'},
	{id:4, title:'Test4'}
]);
console.log('Not IN', db({'id':{'!in':[1,2,3]}}).get().length); // Not IN 1
console.log('IN', db({'id':{'in':[1,2,3]}}).get().length); // IN 3