Changes with nginx 1.5.4 27 Aug 2013

*) Change: the "js" extension MIME type has been changed to
"application/javascript"; default value of the "charset_types"
directive was changed accordingly.

*) Change: now the "image_filter" directive with the "size" parameter
returns responses with the "application/json" MIME type.

*) Feature: the ngx_http_auth_request_module.

*) Bugfix: a segmentation fault might occur on start or during
reconfiguration if the "try_files" directive was used with an empty
parameter.

*) Bugfix: memory leak if relative paths were specified using variables
in the "root" or "auth_basic_user_file" directives.

*) Bugfix: the "valid_referers" directive incorrectly executed regular
expressions if a "Referer" header started with "https://".
Thanks to Liangbin Li.

*) Bugfix: responses might hang if subrequests were used and an SSL
handshake error happened during subrequest processing.
Thanks to Aviram Cohen.

*) Bugfix: in the ngx_http_autoindex_module.

*) Bugfix: in the ngx_http_spdy_module.