Made selector consistent with JS selector.  JS Selector doesn't require .btn-* actions to be within the .actions div.  By pulling the CSS for these buttons outside of .actions, we keep consistent spacing when placing action buttons elsewhere in the wizard markup.
Allow for multiple .steps and multiple .btn's.  This is useful for large forms where, for example, you'd want to put action buttons and steps at the top of the form as well as at the bottom.