Reverted to MigrationId (Timestamp_Name) instead of separate fields/columns.
Add optimistic concurrency tests to ATS provider.
Bug fixes:
RowKey and PartitionKey must use string comparison in queryString.
QueryableConstant expression did not match type when comparing to Nullable objects.
Improve error handling.
Fix bug in optimistic concurrency tests.
Merge branch 'atsconcurrency' into dev