Parameterized recursive inotify

I was testing your dockerfile but as I have a lot of repos, I got this error:

```
Failed to watch /grok/src; upper limit on inotify watches reached!
Please increase the amount of inotify watches allowed per user via `/proc/sys/fs/inotify/max_user_watches'.
```

As I update all my repos once per day, I rather disable recursive watching and trigger the OpenGrok update manually after updating my data.