Support for uint

[DenLilleMand]

I realize that the db driver doesn't support uint as a type and that javascript only have the number type. Basically meaning a rather small performance hit because of the conversion we would need to do, not to mention the complications with overflow.

But i still think in some of the structs we have it would make sense to have a null.Uint just for cosmetic purposes and to enforce correct types at the point of storage to avoid errors. Would a PR with uint type(s) be accepted?

[guregu]

I can see how this would be useful but I'm going to limit the scope of this library to the types the DB drivers support.