Mark todos logic

[shiryz]

The following lines in marktodos function can be more readable and shortened
https://github.com/facn6/week3_finalProject.io/blob/master/skeleton/logic.js#L56

if(item.done == true)
          {
            item.done = false;
          }
          else
          {
            item.done = true;

          }

What you're trying to do is change the state of the todo from true to false and vice versa and this can be done by returning the opposite state

item.done = !item.done;
return item;