Modules - needs to handle a 401 when x-pack is installed and auth fails.

From PH...
```
⚙ ph@sashimi  ~/es/logstash   pr/7378  bin/logstash --modules cef
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
Sending Logstash's logs to /Users/ph/es/logstash/logs which is now configured via log4j2.properties
[2017-06-08T11:48:03,299][INFO ][logstash.setting.writabledirectory] Creating directory {:setting=>"path.queue", :path=>"/Users/ph/es/logstash/data/queue"}
[2017-06-08T11:48:03,304][INFO ][logstash.setting.writabledirectory] Creating directory {:setting=>"path.dead_letter_queue", :path=>"/Users/ph/es/logstash/data/dead_letter_queue"}
[2017-06-08T11:48:03,823][FATAL][logstash.runner ] An unexpected error occurred! {:error=>#, :backtrace=>["/Users/ph/es/logstash/logstash-core/lib/logstash/config/modules_common.rb:61:in `pipeline_configs'", "org/jruby/RubyArray.java:1613:in `each'", "/Users/ph/es/logstash/logstash-core/lib/logstash/config/modules_common.rb:36:in `pipeline_configs'", "/Users/ph/es/logstash/logstash-core/lib/logstash/runner.rb:277:in `execute'", "/Users/ph/es/logstash/vendor/bundle/jruby/1.9/gems/clamp-0.6.5/lib/clamp/command.rb:67:in `run'", "/Users/ph/es/logstash/logstash-core/lib/logstash/runner.rb:209:in `run'", "/Users/ph/es/logstash/vendor/bundle/jruby/1.9/gems/clamp-0.6.5/lib/clamp/command.rb:132:in `run'", "/Users/ph/es/logstash/lib/bootstrap/environment.rb:71:in `(root)'"]}
```