Fixed reordering products table cells

@robertdall reported a bug on #5956 about the reordering of the products. The problem was not happening when you sorted it, but on all cases.

So what was really happening was that all the `tr` elements from the `ui.placeholder` would go messy because  they were not respecting the `ui.item` (original row) attributes, like `style` or `class`, and that might cause problems of them been Hidden (the current bug), or even different widths because of the classes.

**Note:** I've done a bit of rewriting on the JS to follow @claudiosmweb ideas on `.jshintrc` from WP.