Verifies ssl by default.

Fixes #139

Changes behavior to: Default to verifying ssl certificates by OpenSSL's default means, opt-out by adding :verify_ssl => false as an option for the request.

This will likely break situations, albeit undesired, where silent verification failure was occurring but going unnoticed.

Updates tests to reflect that change.

Can somebody make sure the integration tests pass? I don't have the local issuer of the checked-in certs used by those tests, so the tests obviously fail.