OperationsPerInvoke is an informational, not instructional property.
What we actually want is the UnrollFactor. Moved into the job definition
to simplify things.

* Fix for PostgresAdapter in SqlMapperExtensions.Async. Copied same line of code from SqlMapperExtensions to fix RuntimeBinderException on InsertAsync
* Cleanup

Use an HTTPS link where possible.
Fix 404 for performance tests.

* Don't create the connection in Dispose: this avoids creating a SQLConnection simply to Dispose it.
* Run MySQL tests against the open MySqlConnection: 'connection' is a protected variable in the TestBase class that is a SQL Server connection, not a MySQL connection.
* Skip broken MySQL tests: as per issue #295, setting "AllowZeroDateTime=True" in the connection string causes an InvalidCastException in SqlMapper.

More cleanup to do (removing Type column next), but getting to some very
usable output now.

This is based on BenchmarkDotNet (while preserving the legacy format
with minor improvements as well - legacy runs much faster). See #666 for
details. Not an ominus number at all.

Note: this code will get a bit simpler with BenchmarkDotNet categories,
see https://github.com/dotnet/BenchmarkDotNet/issues/248 for details.

It's indeed broken on their end. We should consider switching providers,
e.g. https://github.com/mysql-net/MySqlConnector/

* Progress on VS 2017 build tooling
* Finally, a working VS 2017 tooling build

Add tests for the too few/too many columns scenarios for value-tuples; happy to discuss alternative expectations