Opens megapixel file, if contains '3.5' for instance,
        will scale all uploaded photos in directory this this size,
        the original photo is untouched. Returns None if
        file not found

def _load_megapixels(self,directory):
        """Opens megapixel file, if contains '3.5' for instance,
        will scale all uploaded photos in directory this this size,
        the original photo is untouched. Returns None if
        file not found
        
        """
        #FIXME: should check if DB tracking file before using it

        fullfile=os.path.join(directory,MEGAPIXEL_FILE)
        try:
            mp=float(open(fullfile).readline())
            logger.debug("_load_megapixel: MP from file is %f",mp)
        except:
            logger.warning("Couldn't open image size file in %s, not scaling images"\
                    %(directory))
            return None

        return mp