Fix bug for not firing selection:created when using Shift to add objects

Currently if you use Shift+Click to add objects to a group, selection:created will only fire after you add 3 or more objects to the group. This fix allows selection:created to fire when the group is first created (when the second object is added).
Merge pull request #700 from rileydutton/patch-1

Fix bug for not firing selection:created when using Shift to add objects