Spring MVC

Hello,

This fixes #69 and #68.

* Ported to Spring, and removed the old JAX-RS things.
* Basic user interface for making, editing and listing Jobs.
* User interface is in Bootstrap (#69).
* Implemented end-dating on the datamodel, and many changes resulted from that to the datamodel, too (much of the CRUD stuff is abstracted to the the CRUD abstract class which the other DAOs extend, first committed in 9c74a66).