Fixed #1205 set default nullable in purchase order for strict mode

app/config/version.php

@@ -1,5 +1,5 @@
 <?php
 return array (
-  'app_version' => 'v2.0-150',
-  'hash_version' => 'v2.0-150-g9ba2779',
+  'app_version' => 'v2.0-151',
+  'hash_version' => 'v2.0-151-g4c662b7',
 );

app/database/migrations/2015_09_28_003314_fix_default_purchase_order.php

@@ -0,0 +1,29 @@
+<?php
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class FixDefaultPurchaseOrder extends Migration {
+
+	/**
+	 * Run the migrations.
+	 *
+	 * @return void
+	 */
+	public function up()
+	{
+		DB::statement('ALTER TABLE `'.DB::getTablePrefix().'licenses` MODIFY `purchase_order` varchar(255) DEFAULT NULL;');
+	}
+
+	/**
+	 * Reverse the migrations.
+	 *
+	 * @return void
+	 */
+	public function down()
+	{
+		//
+		DB::statement('ALTER TABLE `'.DB::getTablePrefix().'licenses` MODIFY `purchase_order` varchar(255);');
+	}
+
+}