Bug 28493: Make koha-passwd display the username

Bug 28493: Make koha-passwd display the username

to test...

1/ run command
 $ sudo koha-passwd dev1
 Password for dev1: CraZyPa$$WoRD!!
 Press enter to clear the screen...
 ^C

2/ apply patch

3/ run command again, note 'username' section
 $ sudo koha-passwd dev1
 Username for dev1: koha_dev1  <<<<<<<<<<<<
 Password for dev1: CraZyPa$$WoRD!!
 Press enter to clear the screen...
 ^C

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>