Fail to install

[rafaelfess]

The asdf install dotnet-core 3.0.0 is not working. It seems Microsoft has changed the download links.

I've tried a workaround changing the download URL in bin/install

# From
https://dotnet.microsoft.com/download/dotnet-core/scripts/v1/dotnet-install.sh
# To
https://dotnetwebsite.azurewebsites.net/download/dotnet-core/scripts/v1/dotnet-install.sh

As it seems to have been changed as we can see here, but it doesn't work too.

Here is my terminal output:

$ asdf install dotnet-core 3.0.0
Downloading the CLI installer
Installing the CLI requested version 3.0.0. Please wait, installation may take a few minutes.
/home/rafael/.asdf/installs/dotnet-core/3.0.0/dotnet-install.sh: line 147: VERSION_ID: unbound variable
/home/rafael/.asdf/installs/dotnet-core/3.0.0/dotnet-install.sh: line 205: VERSION_ID: unbound variable
dotnet-install: Downloading link: https://dotnetcli.azureedge.net/dotnet/Sdk/3.0.0/dotnet-sdk-3.0.0-linux-x64.tar.gz
curl: (22) The requested URL returned error: 404 Not Found
dotnet-install: Cannot download: https://dotnetcli.azureedge.net/dotnet/Sdk/3.0.0/dotnet-sdk-3.0.0-linux-x64.tar.gz
dotnet_install: Error: Could not find/download: `.NET Core SDK` with version = 3.0.0
dotnet_install: Error: Refer to: https://aka.ms/dotnet-os-lifecycle for information on .NET Core support
The CLI has been installed.

[emersonsoares]

PR #14 fixes that.