Revert "Revert "Log: Bluetooth Connections""

This reverts commit ec05992c.

Reason for revert: The dummy StatsLog class was merged into stage-aosp-master and oc-mr1-dev-plus-aosp, which were the branches that broke initially.

Change-Id: Ibd082c6bb1e39e2453d59b5a0d8c6ba04047daaa