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/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go b/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go
index bc61084..a014e5e 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/testing/fixtures.go
@@ -61,3 +61,11 @@
 			"53482b62-2c84-4a53-b6ab-30d9d9800d06"))
 	})
 }
+
+func MockDeleteResponse(t *testing.T) {
+	th.Mux.HandleFunc("/share-networks/fa158a3d-6d9f-4187-9ca5-abbb82646eb2", func(w http.ResponseWriter, r *http.Request) {
+		th.TestMethod(t, r, "DELETE")
+		th.TestHeader(t, r, "X-Auth-Token", fake.TokenID)
+		w.WriteHeader(http.StatusAccepted)
+	})
+}