Add FindByAny, Stringer for users

pkg/auth/identity.go

@@ -1,5 +1,9 @@
 package auth
 
+import (
+	"fmt"
+)
+
 type (
 	Identity struct {
 		id       uint64
@@ -30,6 +34,10 @@ func (i Identity) Valid() bool {
 	return i.id > 0
 }
 
+func (i Identity) String() string {
+	return fmt.Sprintf("%d", i.id)
+}
+
 func NewSuperUserIdentity() *Identity {
 	return NewIdentity(superUserID)
 }

pkg/auth/interfaces.go

@@ -9,6 +9,7 @@ type (
 		Identity() uint64
 		Roles() []uint64
 		Valid() bool
+		String() string
 	}
 
 	TokenEncoder interface {