错误提示：
ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError)
SSL_connect returned=1 errno=0 state=SSLv2/v3 read server hello A: sslv3 alert handshake failure (https://gems-ruby-china.b0.aicdn.com/quick/Marshal.4.8/pusher-1.3.1.gemspec.rz)
环境是 Ubuntu 16 LTS
sudo curl -o /usr/share/ca-certificates/cacert.pem https://curl.haxx.se/ca/cacert.pem
sduo dpkg-reconfigure ca-certificates #然后按提示选择 DST Root CA X3这个颁发机构
