Add systemd file

As discussed in OctoPrint#1716

Author: foosel

scripts/README.md

@@ -0,0 +1,17 @@
+# init/systemd files for OctoPrint.
+
+Assumes OctoPrint is installed under user pi at /home/pi/OctoPrint/venv/bin/octoprint. If you have a different
+setup you'll need to adjust octoprint.default (init) or octoprint.service (systemd) accordingly.
+
+## init
+
+```
+octoprint.default   => /etc/default/octoprint
+octoprint.init      => /etc/init.d/octoprint
+```
+
+## systemd
+
+```
+octoprint.service   => /etc/systemd/service/octoprint.service
+```

scripts/octoprint.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=The snappy web interface for your 3D printer
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=pi
+ExecStart=/home/pi/OctoPrint/venv/bin/octoprint
+
+[Install]
+WantedBy=multi-user.target