Implement an https server passing the same tests than http. Except
for test_readv_with_adjust_for_latency of course (hi robert
;-). There is a nasty bug there already triggered in the #158972
days, but nastier this time.

* bzrlib/transport/http/_urllib2_wrappers.py:
(HTTPSConnection.connect_to_origin): Takes python2.6 ssl
implementation into account if available.

* bzrlib/tests/https_server.py:
(TestingHTTPSServer): Real implementation for https.
(HTTPSServer): Real implementation with test ssl files.

* bzrlib/tests/http_server.py:
(HttpServer.create_httpd): New method allowing daughter classes to
create specific servers.