users.Users() no longer takes an argument, so don't try to pass one.

(cherry picked from commit 3f1abc384736f0e105b46612e0601a50784a9528)

This creates an ExecStartPre on the anaconda-sshd.service that will
check for a kickstart entry for sshpw.  It will add/modify users
accordingly prior to launching the sshd service.  Since now sshpw and
sshd bring up happens outside of and before anaconda starts, we can
remove sshd.py and any reference to it.

Mostly replaces 'except Foo, e' with 'except Foo as e', but there
are a few areas where some logic gets reworked.

There were two kinds of unused but set variables:
 - the really pointless ones
 - the ones whose only purpose was to silence the warnings
    about ignoring the return values from functions declared with
    __attribute__((__warn_unused_result__))
Since gcc 4.5 the warnings can be disabled using -Wno-unused-result,
so the variables are no longer necessary.
Then -Wno-unused-but-set-variable is an overkill, so drop it.