Fix a bug in the ownership of evhttp_request objects.
Add an async log client, and base HTTPLogClient on it.
Rename the "ct" C++ namespace to "cert_trans".
Run clang-format on the C++ code.
Fix an incorrect option on my previous clang-format run.
Fix --ct_server arguments to cpp/ct  (now requires a URL)

Also:
* display OpenSSL on startup of test_running_server
* When DER-formatted proof can't be converted to PEM, write a
  message to stderr (but keep on failing)
Merge pull request #176 from trawick/fix-sslconnect-log-url

Fix --ct_server arguments to cpp/ct  (now requires a URL)
Don't use deprecated function.
Fix signed/unsigned warnings.