bugfix: Update handling of cache_control changed in nginx 1.23.0 (Fixes #96) (#97)

bugfix: Update handling of cache_control changed in nginx 1.23.0 (Fixes #96) (#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 #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.