Adding workbench runner

#!/usr/bin/env python

import argparse

from argparse import ArgumentParser

import argparse

from pygriffin import PyGriffin

if __name__ == '__main__':

    ap = ArgumentParser("Runner for Griffin exectuable through PyGriffin")

    ap.add_argument('-i',

                    '--input',

                    type=str, help="SON file")

    ap.add_argument('-l',

                    '--logfile',

                    default=None,

                    type=str, help="Log file")

    args = ap.parse_args()

    pyg = PyGriffin.from_son(args.input)

    # create an input file for the cross sections and provide to pygriffin

    xs_inp_content = "[GlobalParams]\n"

    xs_inp_content += "  library_file = {}\n".format(pyg.xs)

    xs_inp_content += "[]\n"

    with open('isoxml.i', 'w') as xs_inp_file:

        xs_inp_file.write(xs_inp_content)

    pyg.run(other_args=['-i', 'isoxml.i'], logfile=args.logfile)