[CLI] SourceNamespace is not specified if only --source option is provided

$ ./oc infinispan install --source datagrid-catalog
KubernetesClientException: Failure executing: POST at: https://api.rhdg-qe.rhocf-dev.net:6443/apis/operators.coreos.com/v1alpha1/namespaces/openshift-operators/subscriptions. Message: Subscription.operators.coreos.com "datagrid" is invalid: spec.sourceNamespace: Required value. Received status: Status(apiVersion=v1, code=422, details=StatusDetails(causes=[StatusCause(field=spec.sourceNamespace, message=Required value, reason=FieldValueRequired, additionalProperties={})], group=operators.coreos.com, kind=Subscription, name=datagrid, retryAfterSeconds=null, uid=null, additionalProperties={}), kind=Status, message=Subscription.operators.coreos.com "datagrid" is invalid: spec.sourceNamespace: Required value, metadata=ListMeta(_continue=null, remainingItemCount=null, resourceVersion=null, selfLink=null, additionalProperties={}), reason=Invalid, status=Failure, additionalProperties={}).