Backup support for *every* app

We need (mandatory) support for all (new) apps to be backed up. In order to keep track of what is missing here is a List:

• Avahi (no backup needed)
• BIND
• Backups (no backup needed)
• Config (will not be backed up, for now)
• Cockpit (no backup needed)
• Coquelicot
• Datetime
• Deluge
• Diagnostics (no backup needed)
• Dynamic DNS
• ejabberd
• Firewall (no backup needed)
• ikiwiki
• infinoted
• JSXC (no backup needed)
• Let's Encrypt
• Matrix Synapse
• MediaWiki
• Minetest
• MLDonkey
• Monkeysphere
• Mumble
• Names (no backup needed)
• Networks (will not be backed up, for now)
• OpenVPN
• Pagekite
• Power (no backup needed)
• Privoxy (no backup needed)
• Quassel
• Radicale
• repro
• Roundcube (no backup needed)
• SearX (no backup needed)
• Secure Shell Server
• Security
• Shadowsocks
• Sharing
• Snapshot
• Storage (no backup needed)
• Syncthing
• Tahoe-LAFS
• Tiny Tiny RSS
• Tor
• Transmission
• Upgrades
• Users (will not be backed up, for now)