python解决SNIMissingWarning和InsecurePlatformWarning警告

   使用pip安装插件，访问https时，有时会报出SNIMissingWarning和InsecurePlatformWarning警告。
   SNIMissingWarning: An HTTPS request has been made, but the SNI (Subject Name Indication) extension to TLS is not available on this platform.

This may cause the server to present an incorrect TLS certificate, which can cause validation failures. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#snimissingwarning.
  SNIMissingWarning
A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. For more information, see https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
  InsecurePlatformWarning
  urllib3给了我们两种建议，升级你的python27版本至python2.7.9以上，或者使用pyOpenSSL。而我在安装pyopenssl后，依旧会出现上述问题，我同时执行了以下代码
pip install requests[security]
pip install pyopenssl ndg-httpsclient pyasn1

   最后还是通过升级python得到解决，当时版本是2.7.8