Make class name changes backwards compatible

Author: Garbanas

src/lib/ngx-drop/file-drop.component.html

@@ -1,4 +1,5 @@
 <div [className]="dropZoneClassName"
+     [class.over]="isDraggingOverDropZone"
      [class.ngx-file-drop__drop-zone--over]="isDraggingOverDropZone"
      (drop)="dropFiles($event)"
      (dragover)="onDragOver($event)"

src/lib/ngx-drop/file-drop.component.scss

@@ -1,15 +1,18 @@
-.ngx-file-drop__drop-zone {
+.drop-zone {
+//.ngx-file-drop__drop-zone {
   height: 100px;
   margin: auto;
   border: 2px dotted #0782d0;
   border-radius: 30px;
 }
 
-.ngx-file-drop__drop-zone--over {
+.over {
+//.ngx-file-drop__drop-zone--over {
   background-color: rgba(147, 147, 147, 0.5);
 }
 
-.ngx-file-drop__content {
+.content {
+//.ngx-file-drop__content {
   display: flex;
   align-items: center;
   justify-content: center;

src/lib/ngx-drop/file-drop.component.ts

@@ -36,7 +36,7 @@ export class FileComponent implements OnDestroy {
   }
 
   @Input()
-  public dropZoneClassName: string = 'ngx-file-drop__drop-zone';
+  public dropZoneClassName: string = 'ngx-file-drop__drop-zone drop-zone';
   /** @deprecated Will be removed in the next major version. Use `dropZoneClassName` instead. */
   public get customstyle(): string { return this.dropZoneClassName; }
   /** @deprecated Will be removed in the next major version. Use `dropZoneClassName` instead. */
@@ -46,7 +46,7 @@ export class FileComponent implements OnDestroy {
   }
 
   @Input()
-  public contentClassName: string = 'ngx-file-drop__content';
+  public contentClassName: string = 'ngx-file-drop__content content';
   /** @deprecated Will be removed in the next major version. Use `contentClassName` instead. */
   public get customContentStyle(): string { return this.contentClassName; }
   /** @deprecated Will be removed in the next major version. Use `contentClassName` instead. */