refactored some core write operations a bit to support a refactoring of the legacy bulk api in order to allow the development of the new high-level crud api.
CSHARP-1057: Detect "jnote" errors reported by server 2.4.x.
Revert "CSHARP-1057: Detect "jnote" errors reported by server 2.4.x."

See CSHARP-959.

This reverts commit 5c5aaa97d1f84d121a8ca0cba3521c5e1255abda.
Server 2.6 getCmdLineOpts reports --nojournal differently.
CSHARP-1057: Fix unit test.
BulkWriteResult FromCore method needs to check IsModifiedCountAvailable before using the ModifiedCountAvailable property.
Fix unit test for w2 against server 2.4.x.
Fix issue with emulated delete operation when Limit == 0.
Add $code and $scope to the list of exceptions in CollectionElementNameValidator.
Check for null documents in InsertMessageBinaryEncoder.