fix #3207

Because some plateform accept Z and z, but some only accept z…

ref #2948

Also add a e2e test for the list query

Thank you, e2e tests

And make things a little bit clearer

Avoids a conflict between /usr/include/uuid.h and
/usr/local/include/uuid/uuid.h on freebsd

This coverage is probably more useful than the other one, because it’s not
really reasonable to try to cover everything with simple units test (e.g. on
network code etc).
However, we should strive to have 100% coverage with our e2e tests.

This makes it possible to execute an ad-hoc command on a server, with
clients like Gajim, for example.

fix #3209

If anybody knows why fedora accepts both, but it only works with %z on
debian, please tell me.

Because, I don’t know why but, this doesn’t work.

At the moment, result-set-management is not implemented, the whole history
(well, at most 1024 messages) is returned.

Use strftime instead

[skip ci]