Keep failed tests as part of every test run until they are fixed

Currently a green bar doesn't tell you that all tests pass. It tells you that the tests *affected by the last change* pass. To make sure there are no failing tests, you have to restart lein-autoexpect.

With this change lein-autoexpect reloads namespaces with failed tests to make them part of the next run, and a green bar means that *all* tests pass.