Added new page drafts and started image entity attaching

Closes #80.

database/migrations/2016_03_13_082138_image_entities_and_page_drafts.php

@@ -0,0 +1,44 @@
+<?php
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class ImageEntitiesAndPageDrafts extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('images', function (Blueprint $table) {
+            $table->string('entity_type', 100);
+            $table->integer('entity_id');
+            $table->index(['entity_type', 'entity_id']);
+        });
+
+        Schema::table('pages', function(Blueprint $table) {
+            $table->boolean('draft')->default(false);
+            $table->index('draft');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('images', function (Blueprint $table) {
+            $table->dropIndex(['entity_type', 'entity_id']);
+            $table->dropColumn('entity_type');
+            $table->dropColumn('entity_id');
+        });
+
+        Schema::table('pages', function (Blueprint $table) {
+            $table->dropColumn('draft');
+        });
+    }
+}