Merge pull request #4 from michelts/master

Fix README: CACHE_NGINX_USE_LOOKUP_TABLE defaults to False instead of True
rewrite: response.{_get_content(),content}
Merge pull request #8 from torchbox/_get_content-deprecated

rewrite: response.{_get_content(),content}
Remove potential vulnerability in example nginx config.
Further nginx config security tweak.
Added 502 cache_miss handler
Merge pull request #9 from mjbrownie/master

Added 502 cache_miss handler