As glusto-tests needs passwordless ssh configured for all severs
and clients. This can sometime be an issue when you have a large
number of nodes. Adding this tool would enable us to
setup passwordless ssh to all the nodes from any given glusto-tests
config file. The tool is a simple python3 commandline tool which
will take glusto-tests config file and password and use sshpass
and ssh-copy-id to setup passwordless ssh to all nodes from the
master node.

Pasting the help menu of the tool to give a better picture of what
can be done with the tool.
usage: setup_passwordless_ssh [-h] [-c CONFIG_FILE] [-p PASSWORD]
                              [-u USERNAME]

Tool to setup passwordless ssh to all nodes.

optional arguments:
  -h, --help            show this help message and exit
  -c CONFIG_FILE, --config_file CONFIG_FILE
                        A glusto-tests configuration file.
  -p PASSWORD, --password PASSWORD
                        Password of servers.
  -u USERNAME, --username USERNAME
                        User to be used to setup passwordless ssh.

Change-Id: I491cdd975719e29b7e8f43ce548b42f2ad59a4b9
Signed-off-by: kshithijiyer <kshithij.ki@gmail.com>