Feature/progress widget (#760)

* Implemented a new widget to show when operations are occuring in the backend (tasks + progress events). Fixed an oversight on progress reporting where I sent 100F instead of 1F.

* Hooked in more progress events for tasks on the backend. Cleaned up code and integrated some RBS into it. CSS needed.

* Show a colored icon when events are active

* Added some styling to the progress widget

API/SignalR/SignalREvents.cs

@@ -19,5 +19,13 @@
         public const string OnlineUsers = "OnlineUsers";
         public const string SeriesAddedToCollection = "SeriesAddedToCollection";
         public const string ScanLibraryError = "ScanLibraryError";
+        /// <summary>
+        /// Event sent out during backing up the database
+        /// </summary>
+        public const string BackupDatabaseProgress = "BackupDatabaseProgress";
+        /// <summary>
+        /// Event sent out during cleaning up temp and cache folders
+        /// </summary>
+        public const string CleanupProgress = "CleanupProgress";
     }
 }