add systemd contrib & rpm spec

[13werwolf13]

I tried to be useful and decided to do it with what I can do:

contrib/systemd/udpt.conf - default config with comments
contrib/systemd/udpt.service - systemd service unit
contrib/systemd/udpt.sysusers - sysuser & group
contrib/systemd/udpt.tmpfiles - homedir for sysuser
contrib/rpm/opensuse_udpt.spec - rpm spec for opensuse (i use it here)

[13werwolf13]

I would also be grateful if udpt started supporting sd_notify and reporting some information to systemd (like transmission for example), then I could happily replace Type=simple in the service file with Type=notify.
for example, udpt could report how much is tracked now, and other useful information, and most importantly, it could be tracked by systemd itself, not only as running/dead but also the frozen state.

transmission example:

[werwolf@power] ~  
❯ sudo systemctl status transmission-daemon | grep Status
     Status: "Uploading 0,81 KBps, Downloading 1,56 KBps."