Change the call to fetch the user's public key, not mine.

I'd changed this while debugging, but now I have it working (with
sandstorm prs #3180 and #3181 merged locally).

Author: zenhack

server/main.js

@@ -65,7 +65,7 @@ function fetchKeyText() {
         //
         // It would probably still be better to use the expected host here,
         // but just to demo:
-        url: 'http://example.com/users/zenhack/keys',
+        url: 'http://example.com/user/keys',
       }, (err, githubResponse, body) => {
         if(err) {
           reject(err);