[Client] Fix possible goroutine leak.

Running goroutines with pullLayer are blocked to send error of a
pull operation. If we abort pulling without notify them about
cancelation they will get stucked forever. To avoid this possible
leak cancelCh was introduced. In case of abort we close that channel
to notify other goroutines about cancelation.
Adds a test for concurrent storagedriver Write/Read Stream operations

This test is currently failing and Skipped for IPC drivers
Typo fix
Azure: storagedriver stub from inmemory
Azure: Create registry container if not exists
Azure: Implement PutContent, GetContent
Azure: Implement List, Delete
Azure: Implement Move
Azure: Implement ReadStream
Azure: Implement WriteStream with block chunking
Azure: storagedriver code cleanup