Sync strutils from oslo-incubator for mask_password fix

This sync pulls in:
   1131b56 Enable mask_password to handle byte code strings

This is needed because Nova commands are hitting the same
problem Cinder was hitting in bug 1368527 which was fixed
by this strutils update in bug 1366189.

This is not needed in kilo because in kilo Nova has moved
to using the oslo.utils library, which has this fix in it.

Closes-bug: #1366189
Change-Id: I983feea4ac26e34032fa66a4b55f0ce42699ba6a
Merge "Sync strutils from oslo-incubator for mask_password fix" into stable/juno