Add configuration for hub health monitoring.

roles/fedmsg/base/templates/base.py.j2

@@ -1,3 +1,4 @@
+import os
 
 config = dict(
     # Set this to dev if you're hacking on fedmsg or an app locally.
@@ -45,3 +46,5 @@ config = dict(
     zmq_tcp_keepalive_idle=60,
     zmq_tcp_keepalive_intvl=5,
 )
+# This option adds an IPC socket by which we can monitor hub health.
+config['moksha.monitoring.socket'] = 'ipc:///var/run/fedmsg/monitoring-%i.socket' % os.getpid()