osmo-remsim-client: add systemd service script template and etc/default configs

Change-Id: I243f3d8e090d49ca3a1d0a8cf568750b76273c03
diff --git a/contrib/etc_default/osmo-remsim-client-0 b/contrib/etc_default/osmo-remsim-client-0
new file mode 100644
index 0000000..8b70721
--- /dev/null
+++ b/contrib/etc_default/osmo-remsim-client-0
@@ -0,0 +1,6 @@
+# Default settings for osmo-remsim-client This file is sourced by systemd
+
+# Options to pass to osmo-remsim-client
+REMSIM_I="0"
+REMSIM_H="2-1.1"
+REMSIM_c="0"