added date badges (dividers) in messages view

src/widgets/meta-message.jsx

@@ -0,0 +1,41 @@
+// Message bubble with non-payload content, such as an indicator of deleted content or a date stamp.
+
+import React from 'react';
+import { FormattedMessage } from 'react-intl';
+
+export default class MetaMessage extends React.PureComponent {
+  constructor(props) {
+    super(props);
+  }
+
+  render() {
+    let content = null;
+    let bubbleClass = 'bubble';
+    if (this.props.deleted) {
+      // Message represents a range of deleted messages.
+      content = <><i className="material-icons gray">block</i> <i className="gray">
+        <FormattedMessage id="deleted_content"
+          defaultMessage="content deleted" description="Shown when messages are deleted" />
+      </i></>
+      bubbleClass += ' deleted';
+    } else if (this.props.date) {
+      // A date badge.
+      content = <>{this.props.date}</>
+      bubbleClass += ' date';
+    }
+
+    if (!content) {
+      return <>{null}</>
+    }
+
+    return (
+      <li className="meta">
+        <div className={bubbleClass}>
+          <div className="message-content">
+            {content}
+          </div>
+        </div>
+      </li>
+    );
+  }
+};