Add jenkins as host alias to jumpbox-1
Add jenkins as host alias to jumpbox-1

So that scripts (ie sensu alerts) can access Jenkins to eg download
build artifacts.

Related to https://www.pivotaltracker.com/story/show/67409248

[#67409248]

alphagov/pp-puppet,alphagov/pp-puppet,alphagov/pp-puppet,alphagov/pp-puppet