unicorn 4.1.0 - small updates and fixes

* Rack::Chunked and Rack::ContentLength middlewares are loaded
  by default for RACK_ENV=(development|deployment) users to match
  Rack::Server behavior.  As before, use RACK_ENV=none if you want
  fine-grained control of your middleware.  This should also
  help users of Rainbows! and Zbatery.

* CTL characters are now rejected from HTTP header values

* Exception messages are now filtered for [:cntrl:] characters
  since application/middleware authors may forget to do so

* Workers will now terminate properly if a SIGQUIT/SIGTERM/SIGINT
  is received while during worker process initialization.

* close-on-exec is explicitly disabled to future-proof against
  Ruby 2.0 changes [ruby-core:38140]