Fix reverse proxy pattern

[avara1986]

Create a Proxy pattern https://microservices.io/patterns/apigateway.html.
You can run the microservice A in your local machine in http://localhost:5000/my-endpoint/

If you deploy your microservice, in some cases, this microservice runs behind a cluster, a gateway... and this gateway redirect traffic to the microservice with a specific path like yourdomian.com/my-ms-a/my-endpoint/.

This fix understands this path if the gateway send a specific header:

• Traefik with HTTP_X_SCRIPT_NAME https://docs.traefik.io/v2.0/middlewares/headers/
• Nginx and Ingress with HTTP_X_SCRIPT_NAME https://www.nginx.com/resources/wiki/start/topics/examples/forwarded/
• Apache with HTTP_X_SCRIPT_NAME https://stackoverflow.com/questions/55619013/proxy-and-rewrite-to-webapp
• Zuul with HTTP_X_FORWARDER_PREFIX https://cloud.spring.io/spring-cloud-netflix/multi/multi__router_and_filter_zuul.html

[coveralls]

Coverage decreased (-0.06%) to 99.177% when pulling d9c2ab6 on fix/reverse_proxy_pattern into 517e5b6 on master.