Enable SqlDataRecord TVPs on corefx.

[sergiivolchkov]

Dapper's support for passing TVPs as IEnumerable<SqlDataRecord> (contrary to DataTable) using SqlMapper.AsTableValuedParameter or type handlers seem to work perfectly fine on .net core 1.x (tested on 1.1.2 runtime).

One caveat here is that Dapper dependency on System.Data.SqlClient has to be brought back.

[NickCraver]

This is already underway in the https://github.com/StackExchange/Dapper/tree/netstandard2 branch, just waiting on an updated SqlClient preview and Appveyor support before we can merge in and get builds going. The netstandard1.x support will be some ifdef changes, but it's going to be much cleaner to do that after the branch merge. Or if you want to PR against that branch today I'd happily pull and test/accept it :)

[sergiivolchkov]

See #802 :)

[NickCraver]

@sergiivolchkov looking good - thanks for the rebase! We'll try and get this merged in very soon, the netstandard2.0 build blocker on Appveyor is our current issue, but they've got an image so I hope to get it building right this week and merge down into master overall. No problem yanking this into the 2.0 branch as-is while I work on the overall merge though, here we go!

[NickCraver]

Doh, wrong PR - meant to merge #802 and had the wrong tab - merging there.