Use tlsv1 instead of sslv3

Apple's sandbox server appears to work with TLSv1 but not SSLv3. So
use TLSv1.

Note: SSLv23 is more compatible (but, with newer SSL versions,
isn't supposed to actually use the insecure SSLv2 [1]).

[1] http://www.heikkitoivonen.net/blog/2010/08/23/ssl-in-python-2-7/