Tests: use 127.0.0.1 instead of localhost.

Name 'localhost' is ambiguous if ipv6 present on system.
diff --git a/ssi-include-big.t b/ssi-include-big.t
index 50f8066..1123038 100644
--- a/ssi-include-big.t
+++ b/ssi-include-big.t
@@ -45,11 +45,11 @@
     gzip on;
 
     server {
-        listen       localhost:8080;
+        listen       127.0.0.1:8080;
         server_name  localhost;
 
         location /proxy/ {
-            proxy_pass http://localhost:8080/local/;
+            proxy_pass http://127.0.0.1:8080/local/;
         }
         location = /local/blah {
             return 204;