npm install时npm ERR! Error: CERT_UNTRUSTED
解决方法：
npm ERR! Error: CERT_UNTRUSTED
npm ERR! at SecurePair.<anonymous> (tls.js:1370:32)
npm ERR! at SecurePair.EventEmitter.emit (events.js:92:17)
npm ERR! at SecurePair.maybeInitFinished (tls.js:982:10)
npm ERR! at CleartextStream.read [as _read] (tls.js:469:13)
npm ERR! at CleartextStream.Readable.read (_stream_readable.js:320:10)
npm ERR! at EncryptedStream.write [as _write] (tls.js:366:25)
npm ERR! at doWrite (_stream_writable.js:221:10)
npm ERR! at writeOrBuffer (_stream_writable.js:211:5)
npm ERR! at EncryptedStream.Writable.write (_stream_writable.js:180:11)
npm ERR! at write (_stream_readable.js:583:24)
npm ERR! at flow (_stream_readable.js:592:7)
npm ERR! at Socket.pipeOnReadable (_stream_readable.js:624:5)
npm ERR! If you need help, you may report this *entire* log,
npm ERR! including the npm and node versions, at:
npm ERR! <http://github.com/isaacs/npm/issues>
npm ERR! System Linux 3.10.0-514.26.2.el7.x86_64
npm ERR! command "/usr/local/node/0.10.24/bin/node" "/usr/local/node/0.10.24/bin/npm" "install"
npm ERR! cwd /opt/workspace/survey_web_gairui
npm ERR! node -v v0.10.24
npm ERR! npm -v 1.3.21
使用以下命令取消ssl验证：
npm config set strict-ssl false