Add trailing slash to strip path

Nginx strips the path on a reverse proxy route if you add a trailing slash. By
missing out our trailing slashes, reverse proxy routes inside path directives
were failing for missing paths. This commit fixes that issue, fixing the Nucleus
API

Change-Id: I1532c6acfcb3b3969e7bb4af229e4321bc78cdd6
diff --git a/nginx.nix b/nginx.nix
index c6417fc..a5e502c 100644
--- a/nginx.nix
+++ b/nginx.nix
@@ -106,7 +106,7 @@
       else if service.type == "reverseproxy" then
         (lib.recursiveUpdate currentConfig {
           value.locations.${currentPath} = {
-            proxyPass = "http://${service.to}";
+            proxyPass = if currentPath == "/" then "http://${service.to}" else "http://${service.to}/";
             proxyWebsockets = true;
             recommendedProxySettings = true;
           };