Corrected several non-strict comparisons against undefined, unnecessary assignments to undefined, a missing semicolon, and a typo, in the simple backend.
Made test discovery recursive.
Improved error reporting in _writeToDisk.
Corrected config functionality in SimpleBackend.
Added dependency on mkdirp in order to create DB root directories as needed.
Got gzip support closer to working, and improved error reporting.
Added tests for the simple DB backend.