fixes #5: improve autofix (#6)

- in some project setups node.start / node.end is undefined,
  and results in the auto fix outputing invalid code

lib/rules/no-smart-quotes.js

@@ -78,7 +78,7 @@ module.exports = {
                     }
 
                     return [
-                        fixer.replaceTextRange([node.start, node.end], fixed),
+                        fixer.replaceText(node, fixed),
                     ];
                 },
             });