#46 popup on error, rather than redirect

My solution for #46, does a popup on error of the script load, and *always* attempts a script injection as a method of trapping script injection blocking.  We do this on the assumption that if a site is blocking script injection, they're also blocking frame injection, and we can trap for script injection, but in order to trap for it, we can't skip loading the script in the case that the site is already hosting jQuery.