Speed up tests on Windows
Merge pull request #155 from schlamar/speed-up-tests

Speed up tests on Windows
We know best if we support SNI.
Use pyOpenSSL if present.

This gives us SNI goodies on all Python versions.
Fix subjectAltName support.

The SNI/subjectAltName tests have a one big problem: They access the
great big, bad Internet, because I am not sure how to create the
correct certificates for this.

Also, this only works in all cases if pyasn1 and ndg-httpsclient are
installed (parsing DER-encoded binary data extracted from X.509
extensions is not my idea of fun.)