- add message class for help texts

- add migrations for message class
- load messages into vue form for dataset publishing
- check unique email of authors during dataset creation
- adaptions in create-step1.blade.php for tooltip colors
- updated package.json

app/Message.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace App;
+
+use Illuminate\Database\Eloquent\Model;
+
+class Message extends Model
+{
+    //
+}