Fix download-instead-of-redirect issue.
Fix download-instead-of-redirect issue.

See jekyll/jekyll-redirect-from#37
See #108

stefanotorresi/php-fig.github.com,php-fig/php-fig.github.com,stefanotorresi/php-fig.github.com,php-fig/php-fig.github.com,stefanotorresi/php-fig.github.com,stefanotorresi/php-fig.github.com,stefanotorresi/php-fig.github.com,php-fig/php-fig.github.com,php-fig/php-fig.github.com,php-fig/php-fig.github.com