KDav without KIO

[Christian Mollekopf]

Hi,

In order to resolve https://phabricator.kde.org/T5795 and finally get a
sustainable solution for DAV access for Kube/Sink I have ported KDav
from KIO to something based on https://github.com/mhaller/qwebdavlib
respectively QNetworkAccessManager.

You can find the code in the dev/nokio branch (I had to squash all
commits because of commits with non-unix line endings that could not be
pushed).

In it's current state all tests pass and it does what it needs to for
the time being. Some cleanup is still required, but functionally it
seems complete to me.

My question to you is if you agree with this direction and would like to
have that patch in kdav master, or if you'd like to stick with what's
currently in master.

Cheers,
Christian