Add types for job cancellation token
Add support for IJobCancellationToken to the Job class
Add support for cancellation token to the PerformContext class
Paying for technical debts in JobPerformanceProcessFacts
Prepare JobPerformanceProcess to work with canceled jobs

And fix a mistake: occured -> occurred
Add job cancellation support for worker
Job abort implementation based on current state
Remove IJobCancellationToken.IsCancellationRequested
Include worker number to processing state data
Add IStorageConnection.GetStateData method
Additional checks to determine job was aborted to avoid race conditions

Added ServerId and WorkerNumber checks.
Fix for SqlServerConnection.GetStateData query
Merge pull request #103 from odinserj/cancellation-token

Cancellation token