* Added the class attributes indicating the unit ID and the label(plugin custom taxonomy) in each products container output.
* Fixed a bug that the `column` option was saved always as 1 for the first time.
* Refactored the code.

git-svn-id: https://plugins.svn.wordpress.org/amazon-auto-links/trunk@870948 b8457f37-d9ea-0310-8a92-e5e31aec5664