Revert "Update stunnel url."

This reverts commit 66496588.

Use shacache instead

component/stunnel/buildout.cfg

@@ -17,7 +17,7 @@ filename = stunnel-4-hooks.py
 
 [stunnel-4]
 recipe = hexagonit.recipe.cmmi
-url = ftp://ftp.stunnel.org/stunnel/archive/4.x/stunnel-4.50.tar.gz
+url = http://mirror.bit.nl/stunnel/stunnel-4.50.tar.gz
 md5sum = d68b4565294496a8bdf23c728a679f53
 pre-configure-hook = ${stunnel-4-hook-download:location}/${stunnel-4-hook-download:filename}:pre_configure_hook
 configure-options =