Show notification preview italic

Refs #148

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -690,11 +690,15 @@ public class ServiceSynchronize extends LifecycleService {
                         if (!TextUtils.isEmpty(message.subject))
                             sb.append(message.subject).append("<br>");
                         String text = Jsoup.parse(body).text();
+                        if (!TextUtils.isEmpty(text)) {
+                            sb.append("<em>");
                             if (text.length() > HtmlHelper.PREVIEW_SIZE) {
                                 sb.append(text.substring(0, HtmlHelper.PREVIEW_SIZE));
                                 sb.append("…");
                             } else
                                 sb.append(text);
+                            sb.append("</em>");
+                        }
                         mbuilder.setStyle(new Notification.BigTextStyle().bigText(HtmlHelper.fromHtml(sb.toString())));
                     } catch (IOException ex) {
                         Log.e(ex);