changing the properties from getDataRange

+ according to the documentation
+ changed from 'start' and 'end' to 'min' and 'max'

lib/timeline/Core.js

@@ -496,8 +496,8 @@ Core.prototype.getDataRange = function() {
   }
 
   return {
-    start: start,
-    end: end
+    min: start,
+    max: end
   }
 };