Add redis service and dns to monitoring box
Setting up rabbitmq for sensu

We had to switch to the maestrodev fork of librarian-puppet as it has
fixed the difference in version parsing bettwen puppet and
librarian-puppet.

ruby-1.9.1-dev had to also be included as the json-1.8.0 gem requires
building natively
Add a sensu user to rabbitmq

password is defined in the environment.yaml such that it can be
overridden in pp-deployment for each environment
Add sensu server to monitoring role

We push through www to the sensu dashboard through the jump box with
basic auth using the same creds as graphite.
Ensure dns and hosts are setup before all.

Every resource added to puppet will be added to the 'main' Stage. To
ensure dns and hosts classes are executed before anything else, I have
createda Stage called 'system' which will be run before 'main'.
Sensu server should depend on redis and rabbitmq.
Fix lint errors
Remove custom nginx server thanks to system stage
Merge branch 'master' of github.com:alphagov/pp-puppet into sensu
Merge pull request #43 from alphagov/sensu

Setup Sensu