Fix issue with log directives in function output

Changelog for 0.9.4:

• PR #133 Fix log formatting issue 132 by @jcollie

Commits
92353ab Don't use Printf if we aren't prefixing the logs. by @jcollie
7809452 don't pass output as a format string by @jcollie
46cde10 Mention that WSGI tends to require buffering HTTP body by @alexellis

Changes: 0.9.3...0.9.4

Generated by Derek