use .net core sdk preview1 in appveyor

Author: enricosada

appveyor.yml

@@ -4,10 +4,23 @@ init:
   - git config --global core.autocrlf input
 
 environment:
+  global:
+    CLI_VERSION: 1.0.0-preview1-002702 # released preview1
   matrix:
     - BUILD_TARGET: DotnetCliTests
     - BUILD_TARGET: NuGet
 
+install:
+  # .NET Core SDK binaries
+  - ps: $url = "https://dotnetcli.blob.core.windows.net/dotnet/beta/Binaries/$($env:CLI_VERSION)/dotnet-dev-win-x64.$($env:CLI_VERSION.ToLower()).zip"
+  # Download .NET Core SDK and add to PATH
+  - ps: $env:DOTNET_INSTALL_DIR = "$pwd\.dotnetsdk"
+  - ps: mkdir $env:DOTNET_INSTALL_DIR -Force | Out-Null
+  - ps: $tempFile = [System.IO.Path]::GetTempFileName()
+  - ps: (New-Object System.Net.WebClient).DownloadFile($url, $tempFile)
+  - ps: Add-Type -AssemblyName System.IO.Compression.FileSystem; [System.IO.Compression.ZipFile]::ExtractToDirectory($tempFile, $env:DOTNET_INSTALL_DIR)
+  - ps: $env:Path = "$env:DOTNET_INSTALL_DIR;$env:Path"
+
 build_script:
   - ps: dotnet --info
   - cmd: build.cmd %BUILD_TARGET%