Download Refactor (#483)

# Added
- New: Cards when processing a download shows a spinner for the progress of the download

# Changed
- Changed: Downloads now always take the backend filename and are streamed in a more optimal manner, reducing the javascript processing that was needed previously.
==================================

* Started refactor of downloader to be more UX friendly and much faster.

* Completed refactor of Volume download to use a new mechanism. Downloads are streamed over and filename used exclusively from header. Backend has additional DB calls to get the Series Name information to make filenames nice.

* download service has been updated so all download functions use new event based observable. Duplicates code for downloading, but much cleaner and faster.

* Small code cleanup

UI/Web/src/app/shared/_services/utility.service.ts

@@ -1,6 +1,7 @@
 import { Injectable } from '@angular/core';
 import { Chapter } from 'src/app/_models/chapter';
 import { MangaFormat } from 'src/app/_models/manga-format';
+import { Series } from 'src/app/_models/series';
 import { Volume } from 'src/app/_models/volume';
 
 export enum KEY_CODES {
@@ -85,4 +86,28 @@ export class UtilityService {
     }
   }
 
+  isVolume(d: any) {
+    return d != null && d.hasOwnProperty('chapters');
+  }
+
+  isChapter(d: any) {
+    return d != null && d.hasOwnProperty('volumeId');
+  }
+
+  isSeries(d: any) {
+    return d != null && d.hasOwnProperty('originalName');
+  }
+
+  asVolume(d: any) {
+    return <Volume>d;
+  }
+
+  asChapter(d: any) {
+    return <Chapter>d;
+  }
+
+  asSeries(d: any) {
+    return <Series>d;
+  }
+
 }