Vagrantfile: Use same IP for VirtualBox and VMWare

We were using different IP's so you could have these two different types of
boxes running without conflicts, but this is a pretty weird edge case.

Instead, optimize for having a single, well-known endpoint.
Added expires field to job definition

This will be used so jobs created during integration tests
can be garbage collected by the master. It can be passed to
the CLI as an ISO-8601 string.
JobTest now tests the expires field
Merge pull request #54 from spotify/rohan/vagrant

Vagrantfile: Use same IP for VirtualBox and VMWare
ExpiredJobReaper: initial implementation

Periodically poll for expired jobs, and undeploy and remove them.

This should eventually be moved out of the master into its own process.
Merge pull request #52 from spotify/rohan/deadline

Implement job expiration and reaping
Provide more data in endpoint so registrars will have all they need.