Image Upload Feature

Adding image upload to the markdown editor using
jQuery.AjaxFileUpload.js.

upload.php

@@ -0,0 +1,45 @@
+<?php
+
+$whitelist = array('jpg', 'jpeg', 'png', 'gif');
+$name      = null;
+$dir       = 'content/images/';
+$error     = null;
+$timestamp = date('YmdHis');
+$path      = null;
+
+if (is_dir($dir)) {
+} else {
+    mkdir($dir, 0644, true);
+}
+
+if (isset($_FILES)) {
+    if (isset($_FILES['file'])) {
+        $tmp_name = $_FILES['file']['tmp_name'];
+        $name     = basename($_FILES['file']['name']);
+        $error    = $_FILES['file']['error'];
+        $path     = $dir . $timestamp . '-' . $name;
+		
+        $check = getimagesize($tmp_name);
+		
+        if($check !== false) {
+            if ($error === UPLOAD_ERR_OK) {
+                $extension = pathinfo($timestamp . '-' . $name, PATHINFO_EXTENSION);
+                if (!in_array($extension, $whitelist)) {
+                    $error = 'Invalid file type uploaded.';
+                } else {
+                    move_uploaded_file($tmp_name, $dir . $timestamp . '-' . $name);
+                }
+            }
+        }
+        else {
+            $error = "File is not an image.";
+        }
+    }
+}
+
+echo json_encode(array(
+    'path' => $path,
+    'name'  => $name,
+    'error' => $error,
+));
+die();