vcsim: add MakeDirectoryResponse (#938)
vcsim: add MakeDirectoryResponse (#938)

Go ignores the empty response, but Python requires it.

Fixes #937
dougm/govmomi,bruceadowns/govmomi,bruceadowns/govmomi,dougm/govmomi,vmware/govmomi,bruceadowns/govmomi,vmware/govmomi,vmware/govmomi,dougm/govmomi