Fix gevent; tag docker-registry to 0.6.5

Before this PR, gevent would fail with the following:

```
[warn] epoll_wait: Invalid argument
Restarting gevent.core.dispatch() after an error [1]: [Errno 22] Invalid argument
```

This fixes that issue by compiling with `libevent-dev` vs `libevent1-dev`, and tags the registry to a known good version.