set journal mode to wal when creating db. Trying to work around sqlite3.OperationalError: disk I/O error errors in CI that I can't reproduce locally. Also this allows reads to happen while writes are occurring. This should permit using the web interface for browsing while a large write load (e.g. bulk data loading from another tracker) is happening. Right now autogenerating issues locks up the tracker for reading with an error that the database is locked.