Problems with re-running tests

[gossminn]

The tests seem to (sometimes?) mess up the database when adding and removing sites. Perhaps cleaning up fails partially (some stuff hangs in the database after unsubscribing and/or matrices).

[gossminn]

So far can't reproduce the problem yet. However, I did find that running the test while already being subscribed to sites can mess up the tests because the tests assume the 'onmydisk' site to not yet being subscribed to. Solved in 2ae2cd2