Show file upload size limit when uploading files

Also handle errors better.

database/migrations/2016_12_01_173018_add_configurable_upload_limit.php

@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class AddConfigurableUploadLimit extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('nodes', function (Blueprint $table) {
+            $table->unsignedInteger('upload_size')->after('disk_overallocate')->default(100);
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('nodes', function (Blueprint $table) {
+            $table->dropColumn('upload_size');
+        });
+    }
+}