Drop LoginMethod enum

Let clients decide what to put in that field.

protocol.go

@@ -25,12 +25,6 @@ const (
 	LogTypeOTPDisabled    = "otp_disabled"
 )
 
-const (
-	LoginMethodPassword = "password"
-	LoginMethodOTP      = "otp"
-	LoginMethodU2F      = "u2f"
-)
-
 // DeviceInfo holds information about the client device. We use a
 // simple persistent cookie to track the same client device across
 // multiple session.

server/userlog_test.go

@@ -73,7 +73,7 @@ func generateTestLogs(n int, userDevices map[string][]*usermetadb.DeviceInfo) []
 			Username:    u,
 			Service:     choose(randomServices),
 			Type:        usermetadb.LogTypeLogin,
-			LoginMethod: usermetadb.LoginMethodPassword,
+			LoginMethod: "password",
 			Message:     "logged in",
 			Timestamp:   randomTime().UTC(),
 			DeviceInfo:  dev,
@@ -190,7 +190,7 @@ func TestUserlog_AddLog_NoDeviceInfo(t *testing.T) {
 		Username:    u,
 		Service:     choose(randomServices),
 		Type:        usermetadb.LogTypeLogin,
-		LoginMethod: usermetadb.LoginMethodPassword,
+		LoginMethod: "password",
 		Message:     "logged in",
 		Timestamp:   time.Now().UTC(),
 	}