Make FOV apply to the larger window dimension as discussed in #1591.
Remove the setter for .fovy on advice from @bagnell.
Merge remote-tracking branch 'origin/master' into fov

Conflicts:
	Source/Scene/SceneTransitioner.js
	Specs/Scene/PerspectiveFrustumSpec.js
Fix fovy computation.
Fix tests.
Change default view calculation in camera and for the home button.
Refactor CesiumWidget to calculate canvas size earlier.

Previously, the canvas would be left at its default size until the first render.  Now, the size is calculated immediately after adding the canvas to the DOM.
Fix more tests.
Merge pull request #1912 from AnalyticalGraphicsInc/fov

FOV based on longer window dimension