MSSqlServer support

[pietermartin]

Restore MSSqlServer support back.

[pietermartin]

I added back the previous MSSqlServer code but the dialect and driver requires updating.

@ngskevinschmidt, @kunalghosh84, would you be willing to submit a PR to update dialect?

I will gladly work with you to bring the dialect up to date, but someone who actually uses MSSqlServer should maintain the dialect.

The code is on the mssqlserver branch.