Add ability to specify passwords for admin accounts during ranger install only.

1] Currently, when Ranger is installed admin,keyadmin, rangerusersync, rangertagsync users are seeded users and they are not configurable during the install process. This task is to provide a facility to specify the admin users password during ranger install.
2] This feature can only be used once, for changing the admin user password for more than one time, users can use Ranger UI or using change password utility.