RestSpecDownloader uses windows path separator (#4207)

* RestSpecDownloader uses windows path separator

* don't be lazy use Path.Combine'

(cherry picked from commit 17dbd2e)
(cherry picked from commit 4adb9b5)

Author: Mpdreamz

src/CodeGeneration/ApiGenerator/RestSpecDownloader.cs

@@ -60,7 +60,7 @@ private void DownloadJsonDefinitions(Specification spec, IProgressBar pbar)
 
 		private void FindJsonFilesOnListing(Specification spec, string html, IProgressBar pbar)
 		{
-			if (!Directory.Exists(GeneratorLocations.RestSpecificationFolder)) 
+			if (!Directory.Exists(GeneratorLocations.RestSpecificationFolder))
 				Directory.CreateDirectory(GeneratorLocations.RestSpecificationFolder);
 
 			var dom = CQ.Create(html);
@@ -92,7 +92,8 @@ private void WriteToEndpointsFolder(string folder, string filename, string conte
 		{
 			var f = Path.Combine(GeneratorLocations.RestSpecificationFolder, folder);
 			if (!Directory.Exists(f)) Directory.CreateDirectory(f);
-			File.WriteAllText(f + "\\" + filename, contents);
+			var target = Path.Combine(f, filename);
+			File.WriteAllText(target, contents);
 		}
 
 		private class Specification