bugfix: Update handling of cache_control changed in nginx 1.23.0 (Fixes 

openresty#96) (openresty#97)

bugfix: config: we should always use double quotes in [...] condition…

…als.

various coding style fixes caught by ngx-releng.

doc: bumped version to 0.30.

doc: bumped version to 0.29; stated that we work with nginx 1.7.10; b…

…e clearer about the connection pool configurations.

doc: typo fix from javasboy in openresty#27.

doc: bumped version to 0.27 and updated other stuff.

doc: bumped version to 0.26; also stated that we work with nginx 1.5.11.

documented the new feature in srcache_store_skip.

bumped version to 0.24.