Start of animation widget tweaks and clean up.
Merge branch 'playback' into playbackTweaks
Fix build do to missing module import.
Some additional Animation cleanup before major refactoring.
Start of an AnimationViewModel.
Ongoing viewModel refactoring.

Not all widget features work yet and there's still a lot of work to be done.
Merge branch 'playback' into playbackTweaks
Start using knockout.

1. Submit knockout 2.2.1 to Source/ThirdParty
2. Start refactoring Animation (and Cesium widgets in genereal) to use an MVVM architecture.
3. Cleanup Eclipse project to exclude JS validation on all Source/ThirdParty code.
Merge remote-tracking branch 'origin/playback' into playbackTweaks
Ongoing MVVM refactoring

1. Add JulianDate.equals function
2. Make Animation destroyable.
3. Get rid of `ButtonViewModel.enabled` since it's redundant with `Command.canExecute`.
Merge remote-tracking branch 'origin/master' into playbackTweaks
Some cleanup to Animation.js

While there's still plenty of work to do, Animation.js is mostly finished for this go-around.  More cleanup will be done once we merge back into the `playback` branch.
Ongoing refactoring.

1. Delete AnimationController and AnimationControllerSpec.
2. Move required AnimationController functionality to AnimationViewModel.
3. Add a new ClockViewModel to eventually be shared across widgets.
4. Add AnimationViewModelSpec (though tests are a mess).
5. Revert many of the changes to Clock/ClockRange/ClockStep to be closer inline with master.

Still a ton of cleanup to be done.
Merge remote-tracking branch 'origin/playback' into playbackTweaks
Make it possible to share animation between widgets.
Merge branch 'playback' into playbackTweaks
Fix client CZML and Two Viewer Widgets demos, which broke due to changes in animation widget.
First pass on documentation and some minor cleanup.
Rename SYSTEM_CLOCK_DEPENDENT to SYSTEM_CLOCK_MULTIPLIER.
Restore docs for SYSTEM_CLOCK_TIME.