Buildpacks should not create a staging.log

Change-Id: Idda5a5585d9c66b59e76f761d01267df86388cb5
Fix writing mysql2 adapter to database.yml.

Change-Id: Ifee76eec8d3c6f17e22d21c3fe5ec279ff796388
Merge "Fix writing mysql2 adapter to database.yml."