add package install script, move runit rules to subdirectory

runit/rc.local

@@ -0,0 +1,5 @@
+# Default rc.local for void; add your custom commands here.
+#
+# This is run by runit in stage 2 before the services are executed
+# (see /etc/runit/2).
+light -I

runit/rc.shutdown

@@ -0,0 +1,5 @@
+# Default rc.shutdown for void; add your custom commands here.
+#
+# This is run by runit in stage 3 after the services are stopped
+# (see /etc/runit/3).
+light -O