houskeeping.py assumes all months are 30 days

As I understand it, the new member committee membership is defined in terms of having processed an application in the last six months. The code assumes that all months are 30 days long. I'm not sure this is worth fixing in practice, but there was a request to audit the code in question and so I'm writing down what I found. cutoff = now() cutoff = cutoff - datetime.timedelta(days=30 * 6)