Upgrade from 1.2 to 1.3.
<ChangeLog>
*) Change: UTF-8 characters are now allowed in request header field
values.
*) Feature: configuration of the request body size limit.
*) Feature: configuration of various HTTP connection timeouts.
*) Feature: Ruby module now automatically uses Bundler where possible.
*) Feature: http.Flusher interface in Go module.
*) Bugfix: various issues in HTTP connection errors handling.
*) Bugfix: requests with body data might be handled incorrectly in PHP
module.
*) Bugfix: individual PHP configuration options specified via control
API were reset to previous values after the first request in application process.
</ChangeLog>