Changes to StickyHeaders

Hello,
I've made some changes to your StickyHeaders library to prevent multiple headers from stacking on each other and to allow page formatting to be used.  This way the page can have nicely formatted div headers that carry into the sticky headers.

Also, I've tested it with JQuery 1.9.1 and it works fine, I've updated the README to reflect that.

The changes were for a specific site's formatting, but I thought they could be useful to another site.  My JavaScript is not the best, but this code does function.

Thanks,
Andrew Kester