ws: Add missing verification for 'register' API call
ws: Add missing verification for 'register' API call

When the operation is successfully executed, Cloud returns "registered"
message. "error" is returned when message format is invalid.

CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source,CESARBR/knot-service-source