: get( path, header = nil )
: get( path, header = nil ) {|str| .... }
    о path ˤ륨ƥƥޤޤ header  nil
    ǤʤСꥯȤȤˤƤ HTTP إåȤƽ
    ߤޤheader ϥϥåǡ֥إå̾ => ơפΤ褦ʷ
    ʤФޤ

    ͤϡС 1.1 Ǥ HTTPResponse ȥƥƥܥǥʸ
    ǤǤ1.2 Ǥ HTTPResponse ҤȤĤΤߤǤξ硢
    ƥƥܥǥ response.body ޤ

    ֥åȤȤ˸ƤФ줿ϥƥƥܥǥ򾯤Ťĥ֥å
    Ϳޤ

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

        # version 1.1 (bundled with Ruby 1.6)
        response, body = http.get( '/index.html' )

        # version 1.2 (bundled with Ruby 1.7 or later)
        response = http.get( '/index.html' )

        # compatible in both version
        response , = http.get( '/index.html' )
        response.body
        
        # using block
        File.open( 'save.txt', 'w' ) {|f|
            http.get( '/~foo/', nil ) do |str|
              f.write str
            end
        }

