owncloud

Initial work using ownCloud instead of Roundcube. I'm submitting this so you can follow the progress @JoshData 

TODO:
-  [x] Currently nginx fails to load css/images, need to investigate further
-  [x] Set appropriate "upload_max_filesize" and "post_max_size" in php.ini (due to big file upload while using File app in ownCloud)
-  [ ] Fix SMTP settings in ownCloud and z-push (use smtp localhost instead of sendmail)
-  [ ] Schedule a proper cronjob instead AJAX/webcron
-  [x] Hide cluttery output
-  [ ] Imap logins fail, need to investigate further..

@JoshData Need a second opinion here, currently (afaik) we need to provide credentials in order to use the MTA so as I see it we got 2 options

- dont use credentials from localhost (IDK if this is even possible? huge security risk imho)
- create a "no-reply" user with a strong random password for outgoing mail

Above also applys to https://github.com/jkaberg/mailinabox/blob/owncloud/setup/owncloud.sh#L51-L61