Adding support of global bearer token variable.
This update brings global bearer token setting in the postman file.
If you set `use_value` as `{{token}}` in the scribe config file it'll automatically populate it when postman file is generated.
In you postman variables you can set that token automatically when sending login request using Postman's `Tests`. You can set this JS code in Tests tab and JWT token will be automatically populated and used globally by the API.
```javascript
var jsonData = JSON.parse(responseBody);
pm.environment.set("token", jsonData.login.access_token);
```