SMS: Add a switch to use_kannel (or not)

If we don't use kannel, then create the runit link in /etc/service
to run the python esme.

modules/rhizo_base/manifests/init.pp

@@ -90,6 +90,7 @@ class rhizo_base {
   $kannel_port             = hiera('rhizo::kannel_port')
   $kannel_username         = hiera('rhizo::kannel_username')
   $kannel_sendsms_password = hiera('rhizo::kannel_sendsms_password')
+  $use_kannel              = hiera('rhizo::use_kannel', 'yes')
 
   # VOIP provider
   $voip_provider_name = hiera('rhizo::voip_provider_name')