Added an additional parameter for collation to the create_database method

When creating a database you can now optionally specify the collation used instead of having to rely on the server's default collation. The latter is not always ideal when dealing with legacy systems.

I am new to MiniTest and have done my best to create tests that conform to the general style presented. Any pointers would be much appreciated.

Thanks and hoping you'll (eventually) accept this request.

- Louis