* lib/net/http.rb (Net::HTTPHeader#content_type): should return nil when there's no Content-Type.
* lib/net/http.rb (Net::HTTPHeader#sub_type): should return nil when there's no sub Content-Type (e.g. "Content-Type: text").
* lib/net/http.rb (Net::HTTPHeader#type_params): wrongly failed when there's no Content-Type.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@10611 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* lib/net/http.rb: new method Net::HTTPHeader#set_form_data and its alias #form_data=.
* lib/net/http.rb: Net::HTTPHeader#add_header -> add_field (adjustted to Ruby 1.8).
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@8362 b2dd03c8-39d4-4d8f-98ff-823fe69b080e