doc: bumped version to 0.9.12.

bumped internal code version to 0.9.12.

bugfix: init_worker_by_lua*: memory corruptions would happen when no …

…server {} is defined in nginx.conf. this regression had appeared in v0.9.11.

doc: bumped version to 0.9.11; also claimed that we work with nginx 1…

….7.4.

doc: bumped version to 0.9.10.

doc: documented the new full-duplex stream cosocket feature.

bumped version to 0.9.8.

doc: now we have tested with nginx 1.5.12; also put the 0.9.7 release…

… date.

bumped version to 0.9.6.

updated docs for the 0.9.5 release.