[MGM]: Make pool mgm multi-threaded

Eventlet was actually breaking all attempts to multi-thread.

Also fix possible race condition in Admin API servers

Change-Id: Ieea545468b60adb28f965650071b6e5dfd946f00
[API][ADMIN_API]: Improvements to DB driver

* Use native python driver so connection problems don't hang DB
* Change connection algorithm:

Now uses the first DB as a master and will auto failover as required.
It will switch back to the first DB after 60 seconds.

Change-Id: I673503b212f6b6e29306c75beeb3fdbb44bdb488