Own parsing of the batch insert/update result set

[Somnium99]

Another thought, the generated keys doesn't really have to be a long. They could be any type. I made it Long to be consistent with updateAndReturnGeneratedKey, but it would perhaps be more useful if it took an Row -> T as a param for mapping the generated keys from the resultset.

Originally posted by @magott in #52 (comment)

This (i.e - adding Row -> T) is actually very useful, instead of just receiving the ids
As a matter of fact, it can save an additional roundtrip to the db, just to get the extra columns from that table that we batch-inserted values to.

If this is something that can be done, I'd be happy to join as a reviewer.

[seratch]

As far as I know, the type resolution depends on how each JDBC driver works. If someone can enhance this library without bringing any breaking changes to existing apps, I am fine to have the change in future versions.