Add ssh_host support for MacOSX El Capitan.

OS X El Capitan moved the /etc/ssh_* files into /etc/ssh/. This fix
adds a distribution version check for Darwin to set the keydir
appropriately on El Capitan and later.

lib/ansible/module_utils/facts.py

@@ -524,6 +524,9 @@ class Facts(object):
         keytypes = ('dsa', 'rsa', 'ecdsa', 'ed25519')
 
         if self.facts['system'] == 'Darwin':
+            if self.facts['distribution'] == 'MacOSX' and LooseVersion(self.facts['distribution_version']) >= LooseVersion('10.11') :
+                keydir = '/etc/ssh'
+            else:
                 keydir = '/etc'
         else:
             keydir = '/etc/ssh'