[FAB-3162] Add optional secret param

Parameter added to fabric-ca user registration

Change-Id: I3227cfcb9d90e51f694eda14710d3d19a652f946
Signed-off-by: Divyank Katira <Divyank.Katira@securekey.com>

Author: d1vyank

fabric-ca-client/fabricca.go

@@ -62,6 +62,10 @@ type RegistrationRequest struct {
 	Attributes []Attribute
 	// CAName is the name of the CA to connect to
 	CAName string
+	// Secret is an optional password.  If not specified,
+	// a random secret is generated.  In both cases, the secret
+	// is returned from registration.
+	Secret string
 }
 
 // RevocationRequest defines the attributes required to revoke credentials with the CA
@@ -219,6 +223,7 @@ func (fabricCAServices *services) Register(registrar fabricclient.User,
 		Type:           request.Type,
 		MaxEnrollments: request.MaxEnrollments,
 		Affiliation:    request.Affiliation,
+		Secret:         request.Secret,
 		Attributes:     attributes}
 	// Make registration request
 	response, err := identity.Register(&req)