access_token header not found

Summary

access_token header not found on API request when using NGINX

Flectra API use access_token header for authentication. I think since nginx drop headers with underscore it is better to use hyphen "access-token".

Steps to reproduce

1. Install flectra
2. Install Nginx
3. proxy 7073 to 80
4. send API request

Possible fixes

1. change "access_token" to "access-token"