Fix two bugs in simulator & code cleaning

Bug 1: a1-interface is now runing single threaded, so need to setup a standalone callback server to test purpose
Bug 2: need to pass real ip from nginx to upstream main.py

Issue-ID: NONRTRIC-218
Signed-off-by: ecaiyanlinux <martin.c.yan@est.tech>
Change-Id: Ia04cbf6a402aff444f17ddd8e9bd41a19a687791
diff --git a/near-rt-ric-simulator/nginx.conf b/near-rt-ric-simulator/nginx.conf
index 5ba9dbe..f21e173 100644
--- a/near-rt-ric-simulator/nginx.conf
+++ b/near-rt-ric-simulator/nginx.conf
@@ -37,9 +37,13 @@
         ssl_certificate_key /usr/src/app/cert/key.crt;
         ssl_password_file   /usr/src/app/cert/pass;
 
+
         # serve dynamic requests
         location / {
-        proxy_pass      http://localhost:2222;
+            proxy_set_header   Host                 $host;
+            proxy_set_header   X-Real-IP            $remote_addr;
+            proxy_set_header   X-Forwarded-For      $proxy_add_x_forwarded_for;
+            proxy_pass      http://localhost:2222;
         }
     }
     ##