Install systemd services with autotools

Change-Id: Ic4875b74bcf2b6232d915070b77fc202a03ef997
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