Merge pull request #126 from kuba/logging

Refactor logging, "pythonic" DialogHandler
Merge remote-tracking branch 'github/letsencrypt/master' into crypto_util_test
More tests for crypto_util
Remove csr_matches_names.

c.f. #127 and
https://github.com/letsencrypt/lets-encrypt-preview/pull/127#discussion-diff-21613376
Add tests for b64_cert_to_pem
Add tests for make_key