Use ssl._create_unverified_context() only if available
Use ssl._create_unverified_context() only if available

It's only available Python 2.7.9 or later.

BUG=#66
R=nednguyen@google.com

Review URL: https://codereview.appspot.com/289570043 .

chromium/web-page-replay,andrey-malets/web-page-replay,chromium/web-page-replay,andrey-malets/web-page-replay