Progress towards fixing unit tests

These commits are pre-requisites to the travis continuous-integration thing (separate pull request #194).
There are some fixes to the makefile, instructions, and default database location.
Also, a work_in_progress decorator, that we should use to annotate any Unit Tests that we currently expect to fail.
I did a couple. You just add `@work_in_progress` to the line before the unit test definition.

If someone could do that for all the currently failing tests, as a half-way house to actually making them work, we will at least be able to detect changes and extra errors.