Add additional body class functionality as a filter + new filters

Add the additional body classes in the 'proper' WordPress way by filtering core 'body_class'. Adds basic browser detection at the start of the class output and Wonderflux layout description to the end - for example:

<body class="browser-chrome page page-id-2 page-template-default content-with-sidebar-1 sidebar-1-left width-960">

Classes added in example above:
browser-chrome
content-with-sidebar-1
sidebar-1-left width-960

The following filters are also available to control the above output:
wflux_body_class_browser
wflux_body_class_layout (array)