在使用pip进行软件包安装的时候出现问题：
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
解决方法：
mkdir -p ~/.pip
vim ~/.pip/pip.conf
然后输入内容：
[global]
index-url = http://mirrors.aliyun.com/pypi/simple/
[install]
trusted-host = mirrors.aliyun.com
