Move Cesium-hint.js from Apps/Sandcastle/ into a new Apps/Sandcastle/Thirdparty folded
Fix to properly check for 'undefined'

Signed-off-by: andre-nunes <andre.garcia.nunes@gmail.com>
Fix reference to Cesium-hint.js
Exclude new ThirdParty folder from jsHint
Fix path to a simple relative one
Exclude new ThirdParty folder from jsHint. Also fix Cesium-hint.js path on HTML file to a simple relative one