added global rrssbInit for external calls.  eg./ after page unhidden

Should allow people to call window.rrssbInit if page being unhidden. 

Re: https://github.com/kni-labs/rrssb/issues/13 & https://github.com/kni-labs/rrssb/issues/35


(using http://gpbmike.github.io/refresh-sf/ for minification)