Fix: Table selector of 0 wasn't limiting the API to just the first …

…table when using `tables()`

- Error was the loose type checking on the selector
- https://datatables.net/forums/discussion/61468
- Thanks Kevin!

js/api/api.table.js

@@ -45,7 +45,7 @@ var __table_selector = function ( selector, a )
  */
 _api_register( 'tables()', function ( selector ) {
 	// A new instance is created if there was a selector specified
-	return selector ?
+	return selector !== undefined && selector !== null ?
 		new _Api( __table_selector( selector, this.context ) ) :
 		this;
 } );