Adds Kapi.Actor#moveKeyframe. v0.14.1.

Squashed commit of the following:

commit 38f6340583ec20418adb3b8f86faf35b76289d92
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Thu May 30 21:01:00 2013 -0700

    Adds example, adds more documentation, builds v0.14.1.

commit 80874a1afe892fe27a02dc0eb027c743012be1ae
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Thu May 30 20:43:20 2013 -0700

    Refactors some common code.

commit f3b0a3d39ca4173d2cb8b40748e49597a19d2197
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Thu May 30 20:36:17 2013 -0700

    Makes tests pass.

commit 819a23b25e08e9306c197376dc76d90d9860f58a
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Thu May 30 20:24:08 2013 -0700

    Adds another failing test.

commit fee6c4de6556591bdc5eb4ca76f65016eee5a885
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Thu May 30 20:17:58 2013 -0700

    Adds a failing test.

commit 2a155925478f9126ec68294bd8c1fef7304b29ce
Author: Jeremy Kahn <jeremyckahn@gmail.com>
Date:   Thu May 30 20:09:15 2013 -0700

    Adds boilerplate for moveKeyframe and adds a test.