Bugfix urls to EU-S3 buckets.

If you try to address EU-buckets with http://s3.amazonaws.com/bucket/
you get:
	The bucket you are attempting to access must be addressed using
	the specified endpoint. Please send all future requests to this
	endpoint.

Thats why we should let underlying infrastructure form the url as it
might know this kind if things.

ckan/controllers/storage.py

@@ -262,8 +262,9 @@ def get_metadata(self, label):
         if storage_backend in ['google', 's3']:
             if not label.startswith("/"):
                 label = "/" + label
-            url = "https://%s/%s%s" % (self.ofs.conn.server_name(),
-                                       bucket, label)
+            url = "https://%s%s" % (
+                self.ofs.conn.calling_format.build_host(
+                    self.ofs.conn.server_name(), bucket), label)
         else:
             url = h.url_for('storage_file',
                             label=label,