Use update indexes access in Mongoose configuration. Fixes #225

See: https://mongoosejs.com/docs/deprecations.html#ensureindex

Thanks!

src/app.ts

@@ -30,7 +30,7 @@ const app = express();
 const mongoUrl = MONGODB_URI;
 mongoose.Promise = bluebird;
 
-mongoose.connect(mongoUrl, { useNewUrlParser: true} ).then(
+mongoose.connect(mongoUrl, { useNewUrlParser: true, useCreateIndex: true } ).then(
     () => { /** ready to use. The `mongoose.connect()` promise resolves to undefined. */ },
 ).catch(err => {
     console.log("MongoDB connection error. Please make sure MongoDB is running. " + err);