method for generating HTTP/1.1 100 continue response if the client
expects it, otherwise does nothing. Patch by Brian Candler.
ref #855.
* test/webrick/test_httprequest.rb: test added.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@29218 b2dd03c8-39d4-4d8f-98ff-823fe69b080e