Fixes timing issues for tweens that are started after being configured.

Fixes #50.

Squashed commit of the following:

commit 243ac865326793ad76b5cd4802eaa28a38a35990
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Wed Oct 22 21:46:25 2014 -0500

    Builds 1.3.2.

commit 2dc1798cde7a3706abac4e832ce0023f2d155119
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Tue Oct 21 21:09:46 2014 -0500

    Enables tweens to be restarted.