Optimize combined geometry's bounding sphere.
Updates based on review.
Test responseType 'blob' after calling open.  Firefox throws when setting responseType before opening.
Merge pull request #1004 from AnalyticalGraphicsInc/fixLoadImageViaBlobInFirefox

Fix blob-based image loading in Firefox and IE11
Merge pull request #999 from AnalyticalGraphicsInc/geometryBoundingSphere

Optimize Geometry Bounding Sphere
Merge remote-tracking branch 'origin/master' into meshTerrain