HUGE: moved tests to separate apps.

Tests are finally working!  They still spit out lots of errors
(I must have screwed up urls imports somewhere), but they work.

I mostly moved test files to appropriate directories, changing imports
on the fly.  In some cases I decided to split test files in two (e.g.
when they contained TestCases for both models and views).

In one case I did little refactoring (TestCase was injecting
``globals()``).

It's 2:35 AM and I don't remember anything else I might have worked on
today.  So this is not a very helpful commit message.  Sorry.