Cleaned up/simplified DB code
Removed bonecp releaseHelperThreads config

Fixes #1919

* releaseHelperThreads has been deprecated
* we were disabling it anyway
* 0.8.0 now warns if you set it
Merge pull request #1919 from jroper/1919-bonecp-config

play-2.2.1-RC1 - BoneCPConfig - releaseHelperThreads has been deprecated