Bubble up stack trace

Credit to Tom Yeh
https://github.com/tomyeh/postgresql/commit/a9794f7630919bf9c6e9d047eba8e9d3302a72e6
Bubble up connection pool errors

Thanks to Tom Yeh
https://github.com/tomyeh/postgresql/commit/afaec9de3947cd5ff1ae076ec1d51969e154f974
Add error handler for connection pool start.
Clean up pooling test
Remove unused import
Add new pool test
Remove library statements from tests
Fix connection close timeout feature, and add more diagnostic information