Replaced bcrypt-then with updated bcrypt

Author: Jamie Curnow

package.json

@@ -36,7 +36,7 @@
   "dependencies": {
     "ajv": "^6.5.1",
     "batchflow": "^0.4.0",
-    "bcrypt-then": "^1.1.0",
+    "bcrypt": "^3.0.0",
     "body-parser": "^1.18.3",
     "compression": "^1.7.2",
     "config": "^1.30.0",

src/backend/models/auth.js

@@ -3,7 +3,7 @@
 
 'use strict';
 
-const bcrypt = require('bcrypt-then');
+const bcrypt = require('bcrypt');
 const db     = require('../db');
 const Model  = require('objection').Model;
 const User   = require('./user');