Merge remote-tracking branch 'origin/master' into velocity

Conflicts:
	Source/Core/HermitePolynomialApproximation.js
	Source/Core/LinearApproximation.js
	Source/DynamicScene/SampledPositionProperty.js
semiMajorAxis can be negative for hyperbolic orbits.
Mark some things private
Better use of multiple examples in reference doc
Clean up Moon interface
Readonly doc tweak
Merge branch 'private-2' into private
Style tweak
Fixed models to correctly handle Data Uri's for embedded resources.
Removed png image for embeddedDuck model since the model resources are embedded. Also Model._baseUri behave as it should when no basePath is specified.
Derivative tests and fixes.
Fix tests.
Merge branch 'camera-terrain' into pick-terrain
Changes after review.
Merge remote-tracking branch 'origin/master' into north-up
Merge pull request #1785 from AnalyticalGraphicsInc/north-up

North-up viewing of high-orbit objects
Merge remote-tracking branch 'origin/master' into quadtreePrimitive

Conflicts:
	Source/Scene/Globe.js
	Source/Scene/GlobeSurface.js
	Source/Scene/GlobeSurfaceTile.js
	Specs/Scene/TileSpec.js
Doc cleanup.
Merge remote-tracking branch 'origin/master' into velocity
Update CHANGES.