This change adds testcases for Response#inspect and #code_type, and
improves line coverage of lib/net/http/response.rb (91.8 % to 92.94 %).

A patch from @owlworks.  https://github.com/ruby/ruby/pull/1898

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63738 b2dd03c8-39d4-4d8f-98ff-823fe69b080e