Fix for Mono

Author: Morasiu

challenges/19_Count_Words/CountWords.cs

@@ -17,6 +17,6 @@ static void Start() {
   }
 
   static int Count(string sentence) {
-    return sentence.Split(" ", StringSplitOptions.RemoveEmptyEntries).Length;
+    return sentence.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries).Length;
   }
 }