Update check for local salt master

By default the check is OK for a number of processes between 1 and 15
but on our machine the number is up to 48. So we set the limit
accordingly.

Change-Id: Iac3d2b91312dfe778ebcd39b5eb985348c7aee5a

salt/meta/sensu.yml

 check:
   local_salt_master_proc:
-    command: "PATH=$PATH:/usr/lib64/nagios/plugins:/usr/lib/nagios/plugins check_procs -C salt-master -u root -c 1:15"
+    command: "PATH=$PATH:/usr/lib64/nagios/plugins:/usr/lib/nagios/plugins check_procs -C salt-master -u root -c 1:50"
     interval: 60
     occurrences: 1
     subscribers: