beanshell: encode(String) in URLEncoder has been deprecated

http://docs.oracle.com/javase/1.5.0/docs/api/java/net/URLEncoder.html

Change-Id: Ie21fdd12206c7954e99761826f98686c4567aa64
Reviewed-on: https://gerrit.libreoffice.org/10482
Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>