Ensure .NET SDK CAS behaviour is consistent with Java SDK 2.0

This is a reminder to follow up and confirm that the CAS behavior with the .NET SDK 2 and Java SDK 2 are consistent. This is motivated by the following email thread:

Hi Tony,

actually, cas is now baked into the ops and much, much smarter.

Here are the big differences:

• Now need for a separate “gets” op. Every get op fetches the cas into the returned Document.
• The “replace” command automatically uses the cas when it’s found on the Document. Insert and upsert don’t use it.
• If replace with cas suceeds all is good, if not the (documented in the api docs) throws exceptions or errors the observable (CASMismatchException).

Cheers,
Michael