Add Banned usernames model database.

models/bannedUsernames.js

@@ -0,0 +1,18 @@
+const Errors = require('../lib/errors')
+module.exports = (sequelize, DataTypes) =>{
+    let bannedUsernames;
+    bannedUsernames = sequelize.define('bannedUsernames', {
+        // Model attributes are defined here
+        username: {
+            type: DataTypes.STRING,
+            allowNull: false
+        },
+        createdAt: sequelize.DATE,
+        UpdatedAt: sequelize.DATE,
+    }, {
+        // Other model options go here
+    });
+    return bannedUsernames;
+}
+
+