Added doc and support for building behind an HTTP proxy

docs/README-proxy.md

@@ -0,0 +1,29 @@
+===== How to build ONL behind an HTTP Proxy =====
+
+Many corporate environments don't provide native access to the Internet
+and instead all access must go through an HTTP proxy.  Since the ONL
+build process dynamically pulls lots of things, this can be a pain.
+While everyone's setup is different, hopefully these directions help
+reduce that pain.
+
+
+1) Update the git modules to point to http: instead of git:
+
+    sed -i -e 's/git:/http:/' $ONL/.gitmodules
+
+2) Make sure you have apt-cacher-ng installed in your host (non-docker)
+    environment and that docker starts it.  Next, configure it to use
+    your proxy:
+
+     $ grep Proxy /etc/apt-cacher-ng/acng.conf
+     Proxy: http://myproxy.mycompany.com:8080
+     # /etc/init.d/apt-cacher-ng restart
+
+3) Make sure your git config is configured correctly for 
+    proxies:
+
+    $ cat ~/.gitconfig
+    [https]
+        proxy = myproxy.mycompany.com:8080
+    [https]
+        proxy = myproxy.mycompany.com:8080