(GH-1012) Remove "IsText" File Before Check

Ensure that the istext file is not there when we are attempting to
download content any additional times as the new file could have the
correct content type and not be downloading just text.

src/chocolatey.resources/helpers/functions/Get-WebFile.ps1

@@ -197,12 +197,15 @@ param(
         }
       }
 
+      $binaryIsTextCheckFile = "$fileName.istext"
+      if (Test-Path($binaryIsTextCheckFile)) { Remove-Item $binaryIsTextCheckFile -Force -EA SilentlyContinue; }
+
       if ($headers.ContainsKey("Content-Type")) {
         $contentType = $headers['Content-Type']
         if ($contentType -ne $null) {
           if ($contentType.ToLower().Contains("text/html") -or $contentType.ToLower().Contains("text/plain")) {
             Write-Warning "$fileName is of content type $contentType"
-            Set-Content -Path "$fileName.istext" -Value "$fileName has content type $contentType" -Encoding UTF8 -Force
+            Set-Content -Path $binaryIsTextCheckFile -Value "$fileName has content type $contentType" -Encoding UTF8 -Force
           }
         }
       }