Have abstractions of the database and the notification listener in place.
Added more functionality for chaining a build.
Refactored buildable into a single trait.
Moved functions to implement for WholeBuildable into one place.
Should have all the pieces at this point.  Need to glue them together.
Implemented a simple database suitable for testing, and simplified the signatures for the Database trait.
Cleanup up code via `try!`.
Refactoring to expose testing components.
Seems to be working for simple tests.  Still need to implement a coordinated shutdown to allow for proper integration tests.
Separated out work steps, and removed needless dependency on Arc.
The test suite is no longer broken.
Added integration test that does end-to-end testing.