Added Build scripts for KoreBuild

build.ps1

@@ -0,0 +1,67 @@
+$ErrorActionPreference = "Stop"
+
+function DownloadWithRetry([string] $url, [string] $downloadLocation, [int] $retries) 
+{
+    while($true)
+    {
+        try
+        {
+            Invoke-WebRequest $url -OutFile $downloadLocation
+            break
+        }
+        catch
+        {
+            $exceptionMessage = $_.Exception.Message
+            Write-Host "Failed to download '$url': $exceptionMessage"
+            if ($retries -gt 0) {
+                $retries--
+                Write-Host "Waiting 10 seconds before retrying. Retries left: $retries"
+                Start-Sleep -Seconds 10
+
+            }
+            else 
+            {
+                $exception = $_.Exception
+                throw $exception
+            }
+        }
+    }
+}
+
+cd $PSScriptRoot
+
+$repoFolder = $PSScriptRoot
+$env:REPO_FOLDER = $repoFolder
+
+$koreBuildZip="https://github.com/aspnet/KoreBuild/archive/dev.zip"
+if ($env:KOREBUILD_ZIP)
+{
+    $koreBuildZip=$env:KOREBUILD_ZIP
+}
+
+$buildFolder = ".build"
+$buildFile="$buildFolder\KoreBuild.ps1"
+
+if (!(Test-Path $buildFolder)) {
+    Write-Host "Downloading KoreBuild from $koreBuildZip"    
+
+    $tempFolder=$env:TEMP + "\KoreBuild-" + [guid]::NewGuid()
+    New-Item -Path "$tempFolder" -Type directory | Out-Null
+
+    $localZipFile="$tempFolder\korebuild.zip"
+
+    DownloadWithRetry -url $koreBuildZip -downloadLocation $localZipFile -retries 6
+
+    Add-Type -AssemblyName System.IO.Compression.FileSystem
+    [System.IO.Compression.ZipFile]::ExtractToDirectory($localZipFile, $tempFolder)
+
+    New-Item -Path "$buildFolder" -Type directory | Out-Null
+    copy-item "$tempFolder\**\build\*" $buildFolder -Recurse
+
+    # Cleanup
+    if (Test-Path $tempFolder) {
+        Remove-Item -Recurse -Force $tempFolder
+    }
+}
+
+&"$buildFile" $args