WEBAPI 设置上传文件大小

参考资料：https://stackoverflow.com/questions/33399267/cors-error-when-uploading-larger-files

　　　　   https://blog.csdn.net/i2blue/article/details/83892719

单位是 kb

<configuration>
  <system.web>
    <httpRuntime targetFramework="4.6.1" maxRequestLength="20480000" />
    <customErrors mode="Off" />
  </system.web>
</configuration>

单位是 byte  

<configuration>
  <security>
    <requestFiltering >
      <requestLimits maxAllowedContentLength="4294967295" ></requestLimits>
    </requestFiltering>
  </security>
</configuration>