Added iredmail class and used-quota model

postgres/models/used-quota.js

@@ -0,0 +1,30 @@
+/*
+  UsedQuota table in the iRedMail postgres database.
+
+  The constructor cxpects an instantiation of the sequalize class. Returns a
+  Sequelize model.
+*/
+
+'use strict'
+
+const Sequelize = require('sequelize')
+
+class UsedQuota {
+  // Expects an instantiation of the sequalize class. Returns a Sequelize model.
+  constructor (sequelize) {
+    return sequelize.define(
+      'used_quota',
+      {
+        username: { type: Sequelize.STRING, primaryKey: true },
+        bytes: Sequelize.BIGINT,
+        messages: Sequelize.BIGINT,
+        domain: Sequelize.STRING
+      },
+      {
+        timestamps: false
+      }
+    )
+  }
+}
+
+module.exports = UsedQuota