loading updown plugin if required

testing/tests/ikev2/rw-hash-and-url/hosts/dave/etc/strongswan.conf

@@ -2,5 +2,5 @@
 
 charon {
   hash_and_url = yes
-  load = curl aes des sha1 sha2 md5 gmp random x509 pubkey hmac xcbc stroke kernel-netlink
+  load = curl aes des sha1 sha2 md5 gmp random x509 pubkey hmac xcbc stroke kernel-netlink updown
 }