Title: #390: NSS: Add option to disable memcache
@mzidek-rh's patches look good to me and I've fired a couple of CI builds.
I'll add the "Accepted" label after those builds are successfully
@sumit-bose, @lslebodn: IMO does make sense to treat @lslebodn's suggestion as a
different PR, do you guys agree on that?
See the full comment at https://github.com/SSSD/sssd/pull/390#issuecomment-336784728