pass server, client to before/afterEach Mocha hooks

[kschzt]

Hi,

Would be great to do some repetitive startup/shutdown logic (like creating a user and logging in) in the hooks before/after running the actual tests. It would make the test code a lot cleaner too.

Could we pass the server and clients to these functions as well? Is the environment already running at that point?

Thanks.

[apendua]

@kschzt Please see #121