Get with queries not working in IE11 because of code using includes

Get promise throws an error on IE
Object doesn't support property or method 'includes'

The get function wrapped into the promise below will throw an exception on IE

```return new Promise(function(resolve) {
get(config.baseUrl +'/api/xyz')
.set('Accept', 'application/json')
.set('Cache-Control', 'no-store')
.query({ x: y, y: z })
.end(function(error, res) {
if (res.status === 404 || error) {
resolve(null);
} else {
resolve(JSON.parse(res.text));
}
});
});
```

Seeing a lot of `includes` functionality in the code (request-base.js) :
`if (err.code && ERROR_CODES.includes(err.code)) return true;`

`this.url += (this.url.includes('?') ? '&' : '?') + query;`