Prepare Products.Paypal2SalesforceLead 1.5.
Use pyton-dateutil instead of time.strptime to parse
datetimes from PayPal IPNs.  dateutil's parser is flexible enough
to handle the differences in format between the IPN simulator and
a real IPN.  Also, ignore timezones.
time.strptime has a bug http://bugs.python.org/issue22377
so that only GMT, UTC, and local timezone strings are recognized
for the '%Z' format element, causing failures if PayPal is not
set to use the same timezone as Python has for tzname and is
also not using UTC or GMT.
Require python-dateutil 1.5.  Later versions require python2.5+
due to dependency on 'six'.