make sure ssh do not ask password

For some reason, ssh seems to ask for password even when
PasswordAuthentication is set to no, adding PreferredAuthentications
with the 2 options removed do the trick.

lib/ansible/runner/connection_plugins/ssh.py

@@ -73,6 +73,7 @@ class Connection(object):
                                  "-o", "PubkeyAuthentication=no"]
         else:
             self.common_args += ["-o", "KbdInteractiveAuthentication=no",
+                                 "-o", "PreferredAuthentications=hostbased,publickey",
                                  "-o", "PasswordAuthentication=no"]
         if self.user != pwd.getpwuid(os.geteuid())[0]:
             self.common_args += ["-o", "User="+self.user]