Completely overhauled how import exclusions work.

Currently new exclusions can only be added when adding new movies or deleting old ones. Not manually in the settings menu.
Movies can now be hidden in the new discover feature by using the new import exclusions!

src/NzbDrone.Common/Extensions/IEnumerableExtensions.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -80,5 +80,30 @@ namespace NzbDrone.Common.Extensions
         {
             return source.Select(predicate).ToList();
         }
+
+        public static IEnumerable<T> DropLast<T>(this IEnumerable<T> source, int n)
+        {
+            if (source == null)
+                throw new ArgumentNullException("source");
+
+            if (n < 0)
+                throw new ArgumentOutOfRangeException("n",
+                    "Argument n should be non-negative.");
+
+            return InternalDropLast(source, n);
+        }
+
+        private static IEnumerable<T> InternalDropLast<T>(IEnumerable<T> source, int n)
+        {
+            Queue<T> buffer = new Queue<T>(n + 1);
+
+            foreach (T x in source)
+            {
+                buffer.Enqueue(x);
+
+                if (buffer.Count == n + 1)
+                    yield return buffer.Dequeue();
+            }
+        }
     }
 }