Feedback

* position loading spinners vertically centered as well
* disable fields and show loading spinner in setup

What’s missing is the reload after successful connection. I get the success message in the apache log but it’s not propagated to JS somehow, so it doesn’t jump into https://github.com/owncloud/mail/blob/master/js/mail.js#L244

@DeepDiver1975 can you look into that. cc #8