Add basic LDAP bind functionality

app/models/auth/User.model.js

@@ -6,13 +6,23 @@ const AuthUser = require('flitter-auth/model/User')
  * properties here as you need.
  */
 class User extends AuthUser {
+    static get services() {
+        return [...super.services, 'auth']
+    }
+
     static get schema() {
         return {...super.schema, ...{
             // other schema fields here
         }}
     }
 
-    // Other members and methods here
+    async check_password(password) {
+        return this.get_provider().check_user_auth(this, password)
+    }
+
+    get_provider() {
+        return this.auth.get_provider(this.provider)
+    }
 }
 
 module.exports = exports = User