def site_url(str = nil)
      url = Setting.get('site_url')
      str = str[1..-1] if !str.blank? && str[0,1] == '/'
      "#{Setting.get('url_prefix')}#{strip_url(url)}/#{str}"
    end
def site_url(str = nil)
      url = Setting.get('site_url')
      str = str[1..-1] if !str.blank? && str[0,1] == '/'
      "#{Setting.get('url_prefix')}#{strip_url(url)}/#{str}"
    end
Returns the url of site appended with the given string
 Params:
 +str+:: the string to append onto the end of the site url