The recent change to fix the SiteConfiguration changes on version-only

upgrades broke running selective unit tests. This happened because the

test runner, which normally emits post-migrate signals on database

setup, no longer had a way to set up the configuration, or the tools

entries for that matter.
We now initialize the site configuration after Django sets up the

database in the test runner, so that we can have the correct state.
Note that we cannot call finalize_setup(), as we'll still end up with

some state (logging state, at the very least) that's set up wrong, due

due to the Tool import process. This is worth digging into later, but

it wasn't trivial to work around without possibly regressing something

else in this change.
It does, however, set some default state we use for all unit tests

before any transactions begin, to avoid a database write in each test's

setUp().

The entire test suite, and various partial test runs, all run succesfully.