CA-137319: force a cleanup when a TVM cannot be started as a result of a configuration error.

Signed-off-by: Rob Dobson <rob.dobson@citrix.com>
Merge pull request #6 from rdobson/ca-137319

CA-137319: force a cleanup when a TVM cannot be started as a result of a configuration error.
Merge pull request #7 from xenserver/master

Back port CA-137319 to xs64bit.