: post( path, data, header = nil )
: post( path, data, header = nil ) {|str| .... }
    о path ˤ륨ƥƥФʸ data 
    ޤ쥹ݥ󥹤 << ᥽åɤȤä dest ˽
    ޤޤheader  get ᥽åɤƱǤ
    HTTPResponse ֥Ȥ dest ֤ޤ

    ƥ졼ȤƸƤӤ줿Ȥϥƥƥܥǥ򾯤Ť
    ֥åͿޤ

    1.1 Ǥ 3xx (ƻԲǽʥ顼)ФƤ㳰ȯޤξ
    HTTPResponse 㳰֥Ȥ err.response 뤳ȤǤޤ
     1.2 Ǥ㳰ȯޤ

        # version 1.1
        response, body = http.post( '/cgi-bin/search.rb', 'query=subject&target=ruby' )

        # version 1.2
        response = http.post( '/cgi-bin/search.rb', 'query=subject&target=ruby' )

        # compatible in both version
        response , = http.post( '/cgi-bin/search.rb', 'query=subject&target=ruby' )

        # using block
        File.open( 'save.html', 'w' ) {|f|
            http.post( '/cgi-bin/search.rb',
                       'query=subject&target=ruby' ) do |str|
              f.write str
            end
        }

