Added blank paragraph insertion when selecting unsplash/gif image

refs TryGhost/Product#1225

- provides a more obvious continuation point after selecting an image
- added `scrollIntoView` option to `addParagraphAfterCard()` because for large images the cursor in the new paragraph could be pushed out of the visible area

lib/koenig-editor/addon/components/koenig-card-image.js

@@ -252,10 +252,8 @@ export default Component.extend({
             // create undo snapshot when selecting an image
             this.editor.run(() => {
                 saveCard(payload, false);
+                this.addParagraphAfterCard({scrollIntoView: true});
             });
-            this.deselectCard();
-            this.selectCard();
-            this.scrollToCard();
         },
 
         closeImageSelector(reselectParagraph = true) {

lib/koenig-editor/addon/components/koenig-editor.js

@@ -680,7 +680,7 @@ export default Component.extend({
             }
         },
 
-        addParagraphAfterCard(card) {
+        addParagraphAfterCard(card, {scrollIntoView = false}) {
             let editor = this.editor;
             let section = this.getSectionFromCard(card);
             let collection = section.parent.sections;
@@ -700,6 +700,10 @@ export default Component.extend({
 
                 postEditor.setRange(newPara.tailPosition());
             });
+
+            if (scrollIntoView) {
+                run.schedule('afterRender', this, this._scrollCursorIntoView);
+            }
         },
 
         openSelectorComponent(componentName, range) {