[CA-147887] If we try to copy a reg key that doesn't exist, create it

(Used as a workaround because xennet fails to complete its coinstaller
if it can't find all the netsettings keys it expects to copy)

Signed-off-by: Ben Chalmers <Ben.Chalmers@citrix.com>
Merge pull request #98 from benchalmers/ca-147887-3

[CA-147887] If we try to copy a reg key that doesn't exist, create it