Listed prototype.js 1.5.1.2 as safe per CVE-2008-7220

Listed prototype.js 1.5.1.2 as safe per CVE-2008-7220 - security fix was apparently backported to this version according to: http://prototypejs.org/2008/01/25/prototype-1-6-0-2-bug-fixes-performance-improvements-and-security/