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.
Merge pull request #54 from spotify/rohan/vagrant

Vagrantfile: Use same IP for VirtualBox and VMWare
Merge pull request #52 from spotify/rohan/deadline

Implement job expiration and reaping
Minor fixes to JobValidatorTest and SystemTestBase

Just indentation and using a named constant.