TransferRunner discards vital error message information

[pdowler]

In the series of catch statements (line 290+) the error message string used to sendError is just the base required message and discards additional detail from the exception. For example, the AccessControlException message says which node triggered the permission failure, which is required when trying to delete or move a container tree and the lack of write permission is somewhere in the tree.

Probably most of these errors could have the message from the exception suitably appended.