0.1-RC12

• added support for connection health checks on checkout. The health check is only performed if the connection has been checked in for a minimum of idleTimeBeforeHealthCheck. The parameter is set in the Pools.nonBlocking builder.
• added Database.connections method to return a Flowable of connections from the pool. Note that the author has no existing use case for this method but put it in because if you use Database.connection().repeat() to get a Flowable then you end up over-requesting because of the request behaviour (actually subscribe behaviour to be specific) of the repeat operator.