- stopping the fancy and using WP built in is_tax

Why be 'fancy' (which wasn't working) when WordPress provides a built in
helper for this called is_tax. Using it instead and we're getting
expected behaviour.
removing globals we are not using now
fixing indenting and spacing
adding docblock
- fixing spacing and coding standards

This fixes the spacing to conform to WP standards and kills the one line
conditionals which are now NOT acceptable according to WP stanards.
- adding cat slug to body class

Now we have the cat slug added to our array of classes.
formatting clean up
- adds single product id to body class

Uses wp internal get_queried_object and gets the ID of the post so we
have it as a body class.