signal handling broken on 2.7 with requests_futures

[ischneider]

Ctrl-C has no effect and async tasks proceed. See: agronholm/pythonfutures#25

Unless we can work-around with requests_futures or the futures backport is fixed , might need to use a multiprocessing approach.

[kapadia]

@ischneider I just ran into a similar problem with a client i'm writing for the Sentinel archive. It uses requests, no futures, and SIGINT also doesn't work as expected.

Within planet/scripts/__init__.py, it might be worth appending the following to the top of the script.

import signal

def signal_handler(signal_code, frame):
    sys.exit(0)

signal.signal(signal.SIGINT, signal_handler)