Fix the issues reported by phpcs

Hi

I fixed the above errors in below patch please review.

Thanks.

 /**
  * Add a requirement that PHP is compiled with the GD library.
  *
- * @param $phase
+ * @param string $phase
+ *   The phase parameter description.
  *
  * @return array
+ *   An array of values.
  */
 function imageapi_optimize_gd_requirements($phase) {

That is an hook implementation, so its documentation comment is different.

updated patch according to point addressed in #3, please review.

The last patch changes are correct.