Added logfile output option to make.py

from graph import TaskGraph

from machine import machine, Machine

from manager import Manager

import logging

def main(argv):

    assert len(argv) == 4, "Usage: %s <rules.yaml> <targets.yaml> <minutes avail.>"%argv[0]

    if len(argv) > 2 and argv[1] == '-log':

        logging.basicConfig(filename=argv[2], level=logging.DEBUG)

        del argv[1:3]

    assert len(argv) == 4, "Usage: %s [-log logfile.log] <rules.yaml> <targets.yaml> <minutes avail.>"%argv[0]

    rules = read_rules(argv[1])

    with open(argv[2]) as f:

        tgts = yaml.safe_load(f)