Allow renaming of movies that don't have an "Edition" (#432)

Fixes #405

src/NzbDrone.Core/Organizer/FileNameBuilder.cs

@@ -497,7 +497,10 @@ namespace NzbDrone.Core.Organizer
 
         private void AddTagsTokens(Dictionary<string, Func<TokenMatch, string>> tokenHandlers, MovieFile movieFile)
         {
-            tokenHandlers["{Edition Tags}"] = m => CultureInfo.CurrentCulture.TextInfo.ToTitleCase(movieFile.Edition.ToLower());
+            if (movieFile.Edition.IsNotNullOrWhiteSpace())
+            {
+                tokenHandlers["{Edition Tags}"] = m => CultureInfo.CurrentCulture.TextInfo.ToTitleCase(movieFile.Edition.ToLower());
+            }
         }
 
         private void AddReleaseDateTokens(Dictionary<string, Func<TokenMatch, string>> tokenHandlers, int releaseYear)