Overwrite HelpFormatter constructur to extend argument column

Overwrite the HelpFormatter constructor in the class
OpenStackHelpFormatter to modify the default value of the
max_help_position to extend the width of the argument column
in the help output.

example output before this patch:

    configuration-attach
                        Attaches a configuration group to an instance.
    configuration-create
                        Creates a configuration group.
    configuration-default
                        Shows the default configuration of an instance.
    configuration-delete
                        Deletes a configuration group.
    configuration-detach
                        Detaches a configuration group from an instance.

example output after this patch:

    configuration-attach          Attaches a configuration group to an
                                  instance.
    configuration-create          Creates a configuration group.
    configuration-default         Shows the default configuration of an
                                  instance.
    configuration-delete          Deletes a configuration group.
    configuration-detach          Detaches a configuration group from an
                                  instance.

Change-Id: Ia3ad8e9fefca6da40f55ab3de902c015a0d17006
Closes-Bug: #1326471
Merge "Overwrite HelpFormatter constructur to extend argument column"