creating a body class function

simplifies the 'mother of all body tags' code and externalizes it so
it's not in your template files.  Also everything is included in
'class' now instead of class and id which makes it more usable on
larger projects.
includeing the body_class function

instead of having all php inline
removing all usage of ID in favor if class

see http://css-tricks.com/a-line-in-the-sand/