fix coverage script from masking unit test failures (#265)

* add 'set -e' line to fail on error

* create Unmarshal method for DefaultSecRule

* fix portsbinding 'update' unit test

* go fmt

* remove line from debugging
diff --git a/openstack/blockstorage/v1/apiversions/urls.go b/openstack/blockstorage/v1/apiversions/urls.go
index c9cf895..d1861ac 100644
--- a/openstack/blockstorage/v1/apiversions/urls.go
+++ b/openstack/blockstorage/v1/apiversions/urls.go
@@ -1,8 +1,8 @@
 package apiversions
 
 import (
-	"strings"
 	"net/url"
+	"strings"
 
 	"github.com/gophercloud/gophercloud"
 )