nextcloud Upgrade

**Upgrade process**
DO NOT USE WEB-BASED UPGRADE!
- put into Maintenance Mode
    `sudo -u http php /usr/share/nginx/nextcloud/occ maintenance:mode --on`
- stop and/or disable nginx, maybe reboot
    `systemctl disable nginx.service`
- unmount nextcloud data folder:
     `zfs unmount zstore1/nextcloud_data`
- rename /usr/share/nginx/nextcloud folder to nextcloud.old
    `mv nextcloud nextcloud.old`
- download and unzip update into a new nextcloud folder in nginx webroot
    `wget https://download.nextcloud.com/server/releases/nextcloud-15.0.tar.bz2`
    `tar -xjvf nextcloud-15.0.tar.bz2`
- ensure you now have a nextcloud folder
- copy over config.php from old nextcloud to new nexcloud config folder
- copy over nextcloud/apps from old folder
    `cd /usr/share/nginx/nextcloud/apps`
    `cp -r . /usr/share/nginx/nextcloud.old/apps` #copies new apps to old folder for existing
    `cd /usr/share/nginx/nextcloud.old/apps`
    `cp -r . /usr/share/nginx/nextcloud/apps` #copies all back to apps folder
- Make a data folder under nexcloud for the data mount
    `mkdir /usr/share/nginx/nextcloud/data`
- adjust permissions as per https://docs.nextcloud.com/server/13/admin_manual/maintenance/manual_upgrade.html (use http user instead of www-data user in docs)
    `chown -R http:http nextcloud`
    `find nextcloud/ -type d -exec chmod 750 {} \;`
    `find nextcloud/ -type f -exec chmod 640 {} \;`
- remount data folder
    `zfs mount zstore1/nextcloud_data`
- restart/enable nginx and run the upgrade:
    `systemctl enable --now nginx.service`
    `cd nextcloud`
    `sudo -u http php occ upgrade`
- take out of Maintenance Mode
    `sudo -u http php occ maintenance:mode --off`