Add celery worker to backend-app-1
Replace celery with path to celery in venv

This should allow starting celery without an active venv
Don't manage celery worker process in development
Refactor app resource class

This creates a new resource class, python_app, which the gunicorn_app
resource now uses.

This means that python_app can be used without implying a web app, e.g.
for a worker daemon.
Merge pull request #669 from alphagov/add-celery-worker

Add celery worker to backend-app
Declare virtualenv path in gunicorn_app
Merge pull request #672 from alphagov/add-celery-worker

Set virtualenv path in gunicorn_app
Upgrade sensu and module

Successfully provisioned a monitoring-1 and backup-box-1 with this,
after provisioning with master

Settings required for latest puppet module

 - Be explicit about the api
 - Need to specify a version of the sensu plugin gem
 - The puppet module changed the default vhost to not include a slash -
   https://github.com/sensu/sensu-puppet/pull/184

This unfortunately broke our setup, which expected a slash in the vhost.
Add uchiwa puppet module and config

Uchiwa replaces the sensu dashboard

Uchiwa defaults to using port 3000, so set the nginx alerts upstream to use that
Merge pull request #671 from alphagov/sensu-upgrade

Upgrade sensu