osmo-remsim-bankd: add systemd service script and etc/default config

Change-Id: Iefa6e65c7a03b232a124758cf8890b660abf6885
diff --git a/contrib/systemd/osmo-remsim-bankd.service b/contrib/systemd/osmo-remsim-bankd.service
new file mode 100644
index 0000000..58f5435
--- /dev/null
+++ b/contrib/systemd/osmo-remsim-bankd.service
@@ -0,0 +1,14 @@
+[Unit]
+Description=Osmocom Remote SIM BankD
+
+[Service]
+Type=simple
+Restart=always
+EnvironmentFile=/etc/default/osmo-remsim-bankd
+WorkingDirectory=/etc/osmocom
+ExecStart=/usr/bin/osmo-remsim-bankd $BANKD_OPTS
+RestartSec=2
+
+[Install]
+WantedBy=multi-user.target
+