unicorn 4.3.0 - minor fixes and updates

unicorn 4.3.0 - minor fixes and updates

* PATH_INFO (aka REQUEST_PATH) increased to 4096 (from 1024).
  This allows requests with longer path components and matches
  the system PATH_MAX value common to GNU/Linux systems for
  serving filesystem components with long names.

* Apps that fork() (but do not exec()) internally for background
  tasks now indicate the end-of-request immediately after
  writing the Rack response.

Thanks to Hongli Lai, Lawrence Pit, Patrick Wenger and Nuo Yan
for their valuable feedback for this release.