def get_users(self):
raise NotImplementedError<EOL>
Returns a dictionary with the configured users.
The keys of the main dictionary represents the username. The values represent the details
of the user, represented by the following keys:

    * level (int)
    * password (str)
    * sshkeys (list)

The level is an integer between 0 and 15, where 0 is the lowest access and 15 represents
full access to the device.

Example::

    {
        'mircea': {
            'level': 15,
            'password': '$1$0P70xKPa$z46fewjo/10cBTckk6I/w/',
            'sshkeys': [
                'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC4pFn+shPwTb2yELO4L7NtQrKOJXNeCl1je\
                 l9STXVaGnRAnuc2PXl35vnWmcUq6YbUEcgUTRzzXfmelJKuVJTJIlMXii7h2xkbQp0YZIEs4P\
                 8ipwnRBAxFfk/ZcDsN3mjep4/yjN56eorF5xs7zP9HbqbJ1dsqk1p3A/9LIL7l6YewLBCwJj6\
                 D+fWSJ0/YW+7oH17Fk2HH+tw0L5PcWLHkwA4t60iXn16qDbIk/ze6jv2hDGdCdz7oYQeCE55C\
                 CHOHMJWYfN3jcL4s0qv8/u6Ka1FVkV7iMmro7ChThoV/5snI4Ljf2wKqgHH7TfNaCfpU0WvHA\
                 nTs8zhOrGScSrtb mircea@master-roshi'
            ]
        }
    }