[Xenial][PULL] CIFS: Enable encryption for SMB3

[Tim Gardner]

I'm less sanguine about this patch set. Some of these patches are huge,
many of which were not clean cherry picks. Furthermore, this is abusing
our SRU policy in that it is a new feature that is not at all
independent of existing code. While the test results in the Azure
environment look good, I wonder about regressions in other environments.

rtg
-- 
Tim Gardner tim.gardner at canonical.com