Remove reminders when removing piggy bank.

app/models/Piggybank.php

@@ -221,6 +221,14 @@ class Piggybank extends Ardent
         return $this->hasMany('PiggybankEvent');
     }
 
+    /**
+     * @return \Illuminate\Database\Eloquent\Relations\HasMany
+     */
+    public function piggybankreminders()
+    {
+        return $this->hasMany('PiggybankReminder');
+    }
+
     /**
      * Same but for specific date.
      *