Add last message time to sidebar

app/src/components/DateFormatter.tsx

@@ -0,0 +1,14 @@
+import * as React from 'react'
+
+interface Props {
+  date: Date
+}
+
+class DateFormatter extends React.Component<Props, {}> {
+
+  public render() {
+    return <span>{this.props.date.toLocaleDateString()} {this.props.date.toLocaleTimeString()}</span>
+  }
+}
+
+export default DateFormatter