reorder auth interface (#1204)

auth/auth.go

@@ -7,8 +7,6 @@ import (
 
 // Auth providers authentication and authorization
 type Auth interface {
-	// String to identify the package
-	String() string
 	// Init the auth package
 	Init(opts ...Option) error
 	// Options returns the options set
@@ -19,6 +17,8 @@ type Auth interface {
 	Revoke(token string) error
 	// Validate an account token
 	Validate(token string) (*Account, error)
+	// String returns the implementation
+	String() string
 }
 
 // Resource is an entity such as a user or