tools: Enhance password tool usability

Previously the usability of the new password tool was suboptimal. This
patch improves it to get the user more informations and a better
starting point.

Change-Id: Ib2fd12962c82d09fc00748d834c26e5b9051d10f
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=977479
Signed-off-by: Fabian Deutsch <fabiand@fedoraproject.org>