Looks like recent python does not install setuptools, used in drenv
setup.py script. We probably need to switch to more modern library, but
lets first fix the error by installing setuptools. We can look at
modernizing the setup later.

Signed-off-by: Nir Soffer <nsoffer@redhat.com>

The previous command line parsing was too simplistic, resulting in
several problems:

- The filename argument is require for all commands, even the command
  does not use it. Because we validate it, you could not use a dummy
  string or /dev/null.

- Some commands line options have no effect on some commands, but they
  were still documented (e.g. --skip-*)

- Commands had no help

This change fixes the issue by creating a command line parser for every
command, and unifying the command interface to accept only args.
Commands operating on an evnfile load it in the command.

Example help with this change:

    $ drenv --help
    usage: drenv [-h] {start,stop,delete,suspend,resume,dump,fetch,clear} ...

    options:
      -h, --help            show this help message and exit

    commands:
      {start,stop,delete,suspend,resume,dump,fetch,clear}
        start               Start an environment
        stop                Stop an environment
        delete              Delete an environment
        suspend             Suspend virtual machines
        resume              Resume virtual machines
        dump                Dump an environment yaml
        fetch               Cache environment resources
        clear               Cleared cached resources

Help for specific commands:

    $ for cmd in start stop delete suspend resume dump fetch clear; do
        echo
        echo "\$ drenv $cmd --help"; drenv $cmd --help
    done

    $ drenv start --help
    usage: drenv start [-h] [-v] [--name-prefix PREFIX] [--max-workers N] [--skip-tests] [--skip-addons] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile
      --skip-tests          Do not run addons 'test' hooks
      --skip-addons         Do not run addons 'start' hooks

    $ drenv stop --help
    usage: drenv stop [-h] [-v] [--name-prefix PREFIX] [--max-workers N] [--skip-addons] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile
      --skip-addons         Do not run addons 'stop' hooks

    $ drenv delete --help
    usage: drenv delete [-h] [-v] [--name-prefix PREFIX] [--max-workers N] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile

    $ drenv suspend --help
    usage: drenv suspend [-h] [-v] [--name-prefix PREFIX] [--max-workers N] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile

    $ drenv resume --help
    usage: drenv resume [-h] [-v] [--name-prefix PREFIX] [--max-workers N] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile

    $ drenv dump --help
    usage: drenv dump [-h] [-v] [--name-prefix PREFIX] [--max-workers N] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile

    $ drenv fetch --help
    usage: drenv fetch [-h] [-v] [--name-prefix PREFIX] [--max-workers N] filename

    positional arguments:
      filename              path to environment file

    options:
      -h, --help            show this help message and exit
      -v, --verbose         be more verbose
      --name-prefix PREFIX  prefix profile names
      --max-workers N       maximum number of workers per profile

    $ drenv clear --help
    usage: drenv clear [-h] [-v]

    options:
      -h, --help     show this help message and exit
      -v, --verbose  be more verbose

Signed-off-by: Nir Soffer <nsoffer@redhat.com>