Fix method signature, doesn't match security/base.rb

Copied from RI's https://github.com/ripienaar/mcollective-vagrant

On broken server responding to mco ping:
```
E, [2014-01-09T21:52:37.872446 #25854] ERROR -- : agents.rb:138:in `rescue in block in dispatch' Execution of discovery failed: wrong number of arguments (4 for 3)
E, [2014-01-09T21:52:37.872777 #25854] ERROR -- : agents.rb:139:in `rescue in block in dispatch' /Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/security/base.rb:167:in `create_reply'
		/Users/simon/src/marionette-collective/plugins/mcollective/security/none.rb:20:in `encodereply'
		/Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/message.rb:140:in `encode!'
		/Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/runner.rb:128:in `reply'
		/Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/runner.rb:83:in `block in agentmsg'
		/Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/agents.rb:132:in `block (2 levels) in dispatch'
```

From broken client:
```
$ mco ping
W, [2014-01-09T21:51:41.361582 #25854]  WARN -- : runner.rb:71:in `rescue in block in run' Failed to handle message: undefined method `keys' for "ping":String - NoMethodError

W, [2014-01-09T21:51:41.361805 #25854]  WARN -- : runner.rb:72:in `rescue in block in run' /Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/security/base.rb:61:in `validate_filter?'
	/Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/message.rb:211:in `validate'
	/Users/simon/.rvm/gems/ruby-2.1.0@vlad/gems/mcollective-2.2.3/lib/mcollective/runner.rb:120:in `receive'
```