update subprocess call in setup.py

[appukuttan-shailesh]

Fixes installation problem on Windows systems.

Currently users might see the installation getting stuck on running pip install pyNN or locally python setup.py install

Gets stuck at this stage:

This arises from this method in setup.py

def run_command(path, working_directory):
    p = subprocess.Popen(path, shell=True, stdin=subprocess.PIPE,
                         stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                         universal_newlines=True,
                         cwd=working_directory)
    result = p.wait()
    stdout = p.stdout.readlines()
    return result, stdout

On investigating, it was found that the execution gets stuck at result = p.wait()

The use of wait() is potentially problematic. As mentioned in the docs:

This PR takes the above suggestion of replacing wait() with communicate(), and making other related changes.

An alernative workaround, that also I found working, was:

import tempfile

def run_command(path, working_directory):
    with tempfile.NamedTemporaryFile(mode="w+") as tmp_out, tempfile.NamedTemporaryFile(mode="w+") as tmp_err:

        p = subprocess.Popen(path, shell=True, stdin=subprocess.PIPE,
                            stdout=tmp_out, stderr=tmp_err,
                            universal_newlines=True,
                            cwd=working_directory)
        result = p.wait()
        tmp_out.seek(0)
        tmp_err.seek(0)
        stdout = tmp_out.readlines()
    return result, stdout

I would prefer the workaround in the PR more suitable, than the above option.