Make file deletion more reliable

Signed-off-by: Ben Chalmers <Ben.Chalmers@citrix.com>
XenVif #54

Signed-off-by: Ben Chalmers <Ben.Chalmers@citrix.com>
Merge pull request #101 from benchalmers/xenvif54

Xenvif #54

Approved-By: Ben.Chalmers@citrix.com