Handle named queries

[bartlomieju]

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QueryConfig.name is meant to prepare named queries however this parameter is now ignored. Eventually we need to support it, but it's lower priority now.

[hayd]

I was trying to remember if this was the issue I was facing when running examples from node-postgres website. I think, separate issue, their examples should be copied as tests, that way we can be confident the API is consistent.

[bartlomieju]

Good idea