Add Rectangle support to DynamicScene

Still needs specs and cleanup.
Merge branch 'master' into dynamicScene-rectangle
Ongoing DynamicRectangle work

Fix type in CzmlDataSource
Add coordinates property.
DynamicRectangle specs and cleanup.
Update CHANGES.
Clean up DynamicObject order to be easier to maintain.

Also turns out we were missing model proeprties in the constructor.
Simplify reserved property checking DynamicObject.
Merge remote-tracking branch 'origin/master' into dynamicScene-rectangle
A more correct check for reserved property names.
Merge pull request #1629 from AnalyticalGraphicsInc/dynamicScene-rectangle

DynamicScene support for RectangleGeoemtry