Users must be able to change their own passwords

The header displayed in all pages contains the current logged in
user's name; changed that username text into a link to horizon's
in-built user settings dashboard. This dashboard has a panel
by name 'CHANGE PASSWORD' that provides a way to the users to change
their own passwords.

* horizon/horizon_jiocloud/templates/home/nav.html
  + Changed username text into a link to horizon's in-built user's
settings dashboard.

Implements: blueprint change-password