Allow secure user password update.

This patch allows the ability for user password to be updated via
a command prompt so the password doesnt show up in the bash history.
The prompted password is asked twice to verify the match.
If user cntl-D's the prompt a message appears suggesting user to use
either of the options to update the password.

Fixes: bug#938315

Change-Id: I4271ae569b922f33c34f9b015a7ee6f760414e39
(cherry picked from commit f2e0818bc97bfbeba83f6abbb07909a8debcad77)