Display text messages

lib/models/conversation_message.dart

@@ -22,6 +22,8 @@ class ConversationMessage implements Comparable {
         assert(timeInsert != null),
         assert(message != null);
 
+  DateTime get date => DateTime.fromMillisecondsSinceEpoch(timeInsert * 1000);
+
   @override
   int compareTo(other) {
     return id.compareTo(other.id);