Fix build script removing a traling comma. Download into a temp folder.

I made a bad patch with the parameters syntax. I'm making the temp files
go into a subfolder as if the build script stop theres a .tmp that could
be accidentially tracked by source control.

scripts/utils.ps1

@@ -28,7 +28,7 @@ function Delete-Existing ($path) {
 }
 
 function Extract-Archive ($source, $target) {
-    Invoke-Expression "7z x -y -o$($target) $source  > `$null"
+    Invoke-Expression "7z x -y -o$($target) '$source' > `$null"
     if ($lastexitcode -ne 0) {
         Write-Error "Extracting of $source failied"
     }