Added ability to pass options to SqlBulkCopy for bulk insert

[RedDeathGitHub]

Hi!

This is my first contribution, so apologies if this is not done right. I find the library very useful, but I need to pass specific options to SqlBulkCopy when doing bulk insert. So I created this fork to showcase my changes and ask if you find them useful to merge into the main library.

I tried to do this as a non-breaking change, so my additional parameters are all optional - this should not break existing code. All tests seem to pass on my local machine.

Please let me know if you find this a worth-while addition, and please update the nuget version so I would be able to use these changes. Alternatively I'll just use this as a local file library.

Cheers!