Recently Added Chapter Feedback (#1020)

* Added an alt implementation which shows Recently Added chapters. No extra grouping is performed if multiple chapters per volume.

* Started working on a grouping implementation for series.

* Disabled the code for bookmarks cleanup as there is some critical issue in there.

* Implemented a Series Group activity stream which shows recently updated series and providers a count badge showing how many new chapters/volumes were added in that series.

* Removed the bookmark disabling code

* Cleaned up code

* One more code cleanup

API/Entities/Series.cs

@@ -31,7 +31,13 @@ namespace API.Entities
         /// Original Name on disk. Not exposed to UI.
         /// </summary>
         public string OriginalName { get; set; }
+        /// <summary>
+        /// Time of creation
+        /// </summary>
         public DateTime Created { get; set; }
+        /// <summary>
+        /// Whenever a modification occurs. Ie) New volumes, removed volumes, title update, etc
+        /// </summary>
         public DateTime LastModified { get; set; }
         /// <summary>
         /// Absolute path to the (managed) image file