disableWriteAheadLogging() is API level 16.

The function disableWriteAheadLogging() is only documented on API level
16. Currently, this causes the app to crash on start up on some devices,
for instance on a Nexus One.
Merge pull request #130 from flerda/v2.0.2-wal

disableWriteAheadLogging() is API level 16.