Fix Open Cart website so it will run with PHP 5.6

I have an opencart site that for some reason was built on 1.5.1.3 even though 1.5.4 was available at the time. For some reason it looks like that earlier version of Opencart uses PHP 5.2 but my host no longer has that installed. They have told me I need to get the site minimally running on PHP 5.6 for now and eventually PHP 7.

For now I just need to get it running again.