Feature/filestorage sharenetworks delete (#122)

* sfs: Add delete for share networks

* sfs: Make name and descr required for creating share network

* sfs: Add acceptance test for share network Delete

* sfs: Remove required parameters

After taking a close look at the code it appeared that 'name'
and 'description' are not required parameters
diff --git a/acceptance/openstack/sharedfilesystems/v2/sharenetworks_test.go b/acceptance/openstack/sharedfilesystems/v2/sharenetworks_test.go
index 6b74007..e654251 100644
--- a/acceptance/openstack/sharedfilesystems/v2/sharenetworks_test.go
+++ b/acceptance/openstack/sharedfilesystems/v2/sharenetworks_test.go
@@ -6,7 +6,7 @@
 	"github.com/gophercloud/gophercloud/acceptance/clients"
 )
 
-func TestShareNetworkCreate(t *testing.T) {
+func TestShareNetworkCreateDestroy(t *testing.T) {
 	client, err := clients.NewSharedFileSystemV2Client()
 	if err != nil {
 		t.Fatalf("Unable to create shared file system client: %v", err)
@@ -17,7 +17,7 @@
 		t.Fatalf("Unable to create share network: %v", err)
 	}
 
-	// TODO: delete the share network when the delete is implemented
-
 	PrintShareNetwork(t, shareNetwork)
+
+	defer DeleteShareNetwork(t, client, shareNetwork)
 }