Install systemd services with autotools

Change-Id: Ie4c7e81495181059d1dff1c194d52d11fb72ed03
diff --git a/contrib/Makefile.am b/contrib/Makefile.am
new file mode 100644
index 0000000..3439c97
--- /dev/null
+++ b/contrib/Makefile.am
@@ -0,0 +1 @@
+SUBDIRS = systemd