IO::Socket::SSL->start_SSL reqiured ssl_opts.

displayed warnings ( SSL_verify_mode ) when use $furl->env_proxy().

I tested as follows.

    HTTP_PROXY="http://127.0.0.1:8888" perl -I lib xt/200_online/04_ssl.t 
    ok 1 - https://mixi.jp/
    ok 2 - https://mixi.jp
    1..2