support updating gke cluster resources where possible

Hi,

I changed the master authorized networks CIDR blocks and got this error when updating my deployment.

```ERROR: (gcloud.deployment-manager.deployments.update) Error in Operation [operation-....]: errors:
- code: NO_METHOD_TO_UPDATE_FIELD
message: No method found to update field 'cluster' on resource 'gke-us-east1'
of type 'container-v1beta1'. The resource may need to be recreated with the new
field.
- code: NO_METHOD_TO_UPDATE_FIELD
message: No method found to update field 'cluster' on resource 'gke-us-west1'
of type 'container-v1beta1'. The resource may need to be recreated with the new
field.
```