added cashier subscription, subscription plans

app/Models/Plan.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class Plan extends Model
+{
+    protected $fillable = [
+      'name',
+      'description',
+      'product_id',
+      'pricing_id',
+      'price',
+      'monthly_billing',
+      'details'
+    ];
+
+    protected $casts = [
+        'details' => 'json',
+        'monthly_billing' => 'boolean',
+    ];
+}