Ensure djblets.log.tests runs correctly when run standalone
Review Request #9503 — Created Jan. 20, 2018 and submitted
./tests/runtests.py djblets.log.testswould fail due to the
djblets.log.middlewaremodule (which replaces the default debug cursor
wrapper with our own that includes stack traces) was not being imported.
We now just import the module to ensure the code is run.
Ran unit tests, both standalone and entire suite.