Add an nginx proxy service with consul template with the objective of
consolidating all the voltha web UIs on a single port on the host.
This update includes the first UI, portainer. Additional UIs will be
added in subsequent updates. The configuration files are currently
mounted into the container. This is temporary to simplify the
development and addition of other UIs to the proxy configuration. Once
all UIs have been added, the configuration will be copied into the
container.

Change-Id: I218c486b56a627995981489602ab44ae0edf0930
diff --git a/nginx_config/nginx-upstreams.ctmpl b/nginx_config/nginx-upstreams.ctmpl
new file mode 100644
index 0000000..188aa10
--- /dev/null
+++ b/nginx_config/nginx-upstreams.ctmpl
@@ -0,0 +1,5 @@
+upstream api-docker {
+    {{range service "portainer" "any"}}
+    server {{.Address}}:{{.Port}};
+    {{end}}
+}