go1.8: support for additional features

[kardianos]

Many new important features will land in go1.8. Please see document:
https://docs.google.com/document/d/1F778e7ZSNiSmbju3jsEWzShcb8lIO4kDyfKDNm4PNd8/edit?usp=sharing for the full list.

Because these features are new we want drivers to implement them before they are released. Ideally they should be implemented by 2016-12-12 to allow for any driver provided feedback from implementation if necessary.

[ncabatoff]

If no one else has time to work on this before 2016-12-12, I'd be willing to take a stab at it. I'm currently wrapping a very limited interface around database/sql and gofreetds in my dbms_exporter project, and I'd much rather be able to use something standard and more flexible.

[MarkSonghurst]

I don't use gofreetds via it's database/sql interface myself, but many thanks for the generous offer and best of luck :-)