Use the path of the url request in haproxy ACL, because port changes

The request from inside static_web (see docker-compose.yml)
to fox_LB (LB stands for load balancer, see fox_LB/haproxy.cfg) goes
through a nodejs proxy that uses CORS (changeOrigin is set to true
in static/properties.sample.json). This means that the request
port is changed and we have to rely on the request's URL path to
decide which backend to send the request.

In the case of fox service, it seems that frontend balancer can
listen on 8090, but the ACL, defined inside the balancer (see the
fox_LB/haproxy.cfg), uses the new port assigned due to CORS. #33

config/fox_LB/fox_LB_hap.cfg

@@ -22,10 +22,10 @@ frontend fox_balancer
   bind *:8091
   mode http
 
-  acl is_fox url_port 8090
-  acl is_session url_port 8091
-
+  acl is_fox path_dir /fox
   use_backend fox if is_fox 
+
+  acl is_session path_dir /login
   use_backend session if is_session
 
 backend fox