Start client backend through systemd

[zorbathut]

It'd be nice if this package did the grunt work to autostart urbackup, or at least, get it ready to be autostarted. I ended up making /etc/systemd/system/urbackupclientbackend.service based on the Debian .service file in the source repo:

[Unit]
Description=UrBackup Client backend
After=syslog.target network.target

[Service]
ExecStart=/usr/bin/urbackupclientbackend --config /etc/default/urbackupclient --no-consoletime
User=root

[Install]
WantedBy=multi-user.target

It'd also be cool if it had a good option for automatically starting the GUI. I don't know what the best way to accomplish that is, though.