Merge pull request #6 from coralsio/postgress-support

add nullable for code of transaction column

Author: saeed-corals

src/Common/database/migrations/CreateTransactionsTable.php

@@ -17,7 +17,7 @@ public function up()
     {
         Schema::create('payment_transactions', function (Blueprint $table) {
             $table->increments('id');
-            $table->string('code');
+            $table->string('code')->nullable();
 
             $table->morphs('owner');