`wait_for()` is used above in `wait_for_web_ui()`. The `sleep(3)` that is present here, in `is_web_ui_running()`, is there to wait between individual checks - it's not used to wait for anything in particular.

I added this, because what would sometimes happen during update testing is that the test would be waiting for a web ui to go down - it would appear to be down - then it would wait for the web ui to go up again - and it would be back up in a second. However, when trying to access it, it would actually be down.

This takes care of that.