fix(footer.html): prevent "upload now" button click handler from being executed twice in IE9
 IE9 apparently executes a script when you set the src attribute of the tag, and then executes it again when you add the same script tag to the DOM.  In footer.html, we build each Fine Uploader demo dynamically by looking for some cues in the DOM associated with each demo container.  Part of this process involves building a script tag, setting the src attribute of this tag to the associated javascript file responsible for instantiating the demo's Fine Uploader instance, and then we add this script tag to the DOM.  By simply adding the script tag to the DOM and THEN setting the src attribute, we can avoid executing each script (and therefore adding 2 click handlers for each "upload now" button).