Add dynamic resizing to Cesium Viewer layout

Use media queries to provide 3 different configurations based on screen width.  We still need to manually place the centralBody logo because it's currently not stylable by CSS. This makes the widget look better when embedded or on smaller resolution screens.

Hopefully everyone likes the sizes I picked, but if not, please suggest some new ones.
Remove need to call Timeline.updateFromClock.

Register for the `Clock.onTick` event instead, which was introduced with the animation branch.

This is a minor tweak to bring Timeline in line with other widgets (event driven rather than manual updates from the user).  I plan on looking into refactoring Timeline to use knockout/viewModels soon, but I thought this was a good simple change in the mean time.
Merge pull request #535 from AnalyticalGraphicsInc/updateFromClock

Remove need to call Timeline.updateFromClock.
Change resize bounds from 1200 to 900.
Merge pull request #533 from AnalyticalGraphicsInc/dynamicResize

Add dynamic resizing to Cesium Viewer layout
Merge branch 'master' into fullScreen

Conflicts:
	Source/Widgets/Dojo/CesiumViewerWidget.css
Fix merge.