windows更新elasticsearch证书

1. 注册免费证书 https://register.elastic.co/xpack_register
2. 更新
   参考 这里 https://www.elastic.co/guide/en/x-pack/current/installing-license.html

但是由于是在windows下，最后一步需要变通一下
我们用powershell来完成这一步
https://msdn.microsoft.com/en-us/powershell/reference/5.1/microsoft.powershell.utility/invoke-restmethod

PS E:> Invoke-WebRequest -Method Put 'http://{host}:{port}/_xpack/license?acknowledge=true' -ContentType: applicat
ion/json -InFile license.json -Credential elastic