Feature Request: Connection Pooling

[jlloyd-widen]

If this is coming from the SDK out the box, please disregard. I'm currently having problems with my current implementation of tap-mysql with an unexplainable connection timed out error. I believe this could be remedied by implementing connection pooling which was never implemented in any of the pymysql versions of this tap before it. I believe utilizing connection pooling will make the tap more robust overall.