about ssl access error for setup.ps1

My platform is windows 10, powershell version is 4.0:

I use admin command line, try to run setup.ps1, and get errors of SSL access:

```
::: ERRORS
Server access Error: java.security.NoSuchAlgorithmException: Default SSLContext not available url=https://dl.bintray.com/foundweekends/maven-releases/org/foundweekends/conscript/conscript_2.11/0.5.0/conscript_2.11-0.5.0.pom

Server access Error: java.security.NoSuchAlgorithmException: Default SSLContext not available url=https://dl.bintray.com/foundweekends/maven-releases/org/foundweekends/conscript/conscript_2.11/0.5.0/conscript_2.11-0.5.0.jar

Server access Error: java.security.NoSuchAlgorithmException: Default SSLContext not available url=https://oss.sonatype.org/content/repositories/releases/org/foundweekends/conscript/conscript_2.11/0.5.0/conscript_2.11-0.5.0.pom

Server access Error: java.security.NoSuchAlgorithmException: Default SSLContext not available url=https://oss.sonatype.org/content/repositories/releases/org/foundweekends/conscript/conscript_2.11/0.5.0/conscript_2.11-0.5.0.jar

Server access Error: java.security.NoSuchAlgorithmException: Default SSLContext not available url=https://repo1.maven.org/maven2/org/foundweekends/conscript/conscript_2.11/0.5.0/conscript_2.11-0.5.0.pom

Server access Error: java.security.NoSuchAlgorithmException: Default SSLContext not available url=https://repo1.maven.org/maven2/org/foundweekends/conscript/conscript_2.11/0.5.0/conscript_2.11-0.5.0.jar
```

I think it should do some setting for SSL connection, can not directly use System.Net.WebClient。
it should added something between those line in setup.ps1.
···
$wc = New-Object System.Net.WebClient
...
$wc.DownloadFile($url, "$CS/$LJ")
···

从 setup.ps1 以及 System.Net.WebClient 的创建和 DownloadFile 调用开始，然后使用报告中显示的 URL，在 Windows 10 和 PowerShell 4.0 上重现该失败。完成的标准是 setup 过程可以访问这些 HTTPS 工件 URL，而不会出现报告中的 Default SSLContext 错误。

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