upgrade pypy tests to 2.7.8

Fix #497.
Merge pull request #508 from gevent/pypy_tests

upgrade pypy tests to 2.7.8
Remove SSL3 entirely as default TLS level
Merge pull request #517 from Ivoz/rm-ssl3

Remove SSL3 entirely as default TLS level
Skip trying to build gevent for metadata requests

Fixes #490
Merge pull request #519 from Ivoz/nocython-setup

Skip trying to build gevent for metadata requests
upgrade config.{guess/sub} to most recent

from http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD and
http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD