Add the ability to switch from email to ldap and back

model/ldap.go

@@ -0,0 +1,8 @@
+// Copyright (c) 2016 Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package model
+
+const (
+	USER_AUTH_SERVICE_LDAP = "ldap"
+)