Specs for DynamicMaterialProperty

Fixed a bug where it would call a non-prototype function on a prototype object.
DynamicMaterialPropertySpec should be in the WebGL category.
Merge remote-tracking branch 'origin/master' into czmlMaterials
Merge pull request #478 from AnalyticalGraphicsInc/czmlMaterials

Specs for DynamicMaterialProperty
Merge remote-tracking branch 'origin/master' into jasmine-usability