tools: Providing a way to reset change password msg

By not providing any entry when prompted, and just press enter
a user can reset an already set "change password msg"

Bug-Ur: https://bugzilla.redhat.com/1063870
Change-Id: Ic9a93b78af23cd9d44ddcd4a32cd23db80be969a
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>