(GH-622) Remove NuGet temp folders

`TEMP\NuGetScratch` and sometimes a `TEMP\x\Nuget` folder are created
by NuGet Core, however it doesn't clean up after itself on this. It is
expected for you to call `OptimizedZipPackage.PurgeCache()`, but this
does not appear to actually remove the folder because PurgeCache is
dependent on the GUID that it creates for the subdirectory. It doesn't
hold a reference to that and so it comes up with one that doesn't exist
by the time we call it.

Handle cleaning up those caches at the end of most runs.

src/chocolatey/infrastructure.app/runners/GenericRunner.cs

@@ -19,6 +19,7 @@ namespace chocolatey.infrastructure.app.runners
     using System;
     using System.Linq;
     using System.Collections.Generic;
+    using filesystem;
     using SimpleInjector;
     using adapters;
     using attributes;
@@ -139,6 +140,28 @@ public void run(ChocolateyConfiguration config, Container container, bool isCons
                 this.Log().Debug("_ {0}:{1} - Normal Run Mode _".format_with(ApplicationParameters.Name, command.GetType().Name));
                 command.run(config);
             }
+
+            remove_nuget_cache(container);
+        }
+
+        /// <summary>
+        /// if there is a NuGetScratch cache found, kill it with fire
+        /// </summary>
+        /// <param name="container">The container.</param>
+        private void remove_nuget_cache(Container container)
+        {
+            try
+            {
+                var fileSystem = container.GetInstance<IFileSystem>();
+                var scratch = fileSystem.combine_paths(fileSystem.get_temp_path(), "NuGetScratch");
+                fileSystem.delete_directory_if_exists(scratch, recursive: true, overrideAttributes: true, isSilent: true);
+                var nugetX = fileSystem.combine_paths(fileSystem.get_temp_path(), "x", "nuget");
+                fileSystem.delete_directory_if_exists(nugetX, recursive: true, overrideAttributes: true, isSilent: true);
+            }
+            catch (Exception ex)
+            {
+                this.Log().Debug(ChocolateyLoggers.Important, "Not able to cleanup NuGet temp folders. Failure was {0}".format_with(ex.Message));
+            }
         }
 
         public IEnumerable<T> list<T>(ChocolateyConfiguration config, Container container, bool isConsole, Action<ICommand> parseArgs)