Changes with nginx 1.1.7 31 Oct 2011

*) Feature: support of several resolvers in the "resolver" directive.
Thanks to Kirill A. Korinskiy.

*) Bugfix: a segmentation fault occurred on start or while
reconfiguration if the "ssl" directive was used at http level and
there was no "ssl_certificate" defined.

*) Bugfix: reduced memory consumption while proxying of big files if
they were buffered to disk.

*) Bugfix: a segmentation fault might occur in a worker process if
"proxy_http_version 1.1" directive was used.

*) Bugfix: in the "expires @time" directive.