webrick: prevent response splitting and header injection
Original patch by tenderlove (with minor style adjustments).
* lib/webrick/httpresponse.rb (send_header): call check_header
(check_header): raise on embedded CRLF in header value
* test/webrick/test_httpresponse.rb
(test_prevent_response_splitting_headers): new test
* (test_prevent_response_splitting_cookie_headers): ditto
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@63022 b2dd03c8-39d4-4d8f-98ff-823fe69b080e