WIP Py3 dsdb lock

[github at samba.org]

New comment by noelpower on Samba Github repository

https://github.com/samba-team/samba/pull/161#issuecomment-384890698
Comment:
Changing the name of this patch set, using this branch for visibility/testing purposes. I'll try to keep this branch up to date (and will rebase as necessary) with current WIP patches from my own work.
Currently I am in the process of porting individual tests, I am trying to identify wider and more generic changes from the changes necessary to get the tests to run, as I do that I am pulling those changes out into separate pull requests)