Implement ImagesController

RFC @sobering and @johnTurknett — This PR is still a *WORK IN PROGRESS* so please do not merge.  I wanted to get something started in the hopes of building some momentum, this is the beginning of the `ImagesController`.

This PR is progress towards closing out #11.
In the name of MVP I started with a _very_ basic response.  Obviously this will be improved as we iterate on our idea.