Garbidge left after moderator_voice_list

[arcusfelis]

Presence stanzas from Carol can be received in next tests.
There are two ways to solve this:

1. split group "moderator" into two: with and without Carol.
2. wait for an empty room in init_per_testcase.

[arcusfelis]

escalus_bosh:stop/1 is async (does not wait a reply from the server). It may cause this behavior.

[michalwski]

@arcusfelis, could you please verify it's fixed with newest versions of esl/escalus and esl/ejabberd_tests