added upload_of validation rule.

system/input.php

@@ -69,6 +69,18 @@ class Input {
 		return Arr::get(Session::get('laravel_old_input', array()), $key, $default);
 	}
 
+	/**
+	 * Get an item from the uploaded file data.
+	 *
+	 * @param  string  $key
+	 * @param  mixed   $default
+	 * @return array
+	 */
+	public static function file($key, $default = null)
+	{
+		return Arr::get($_FILES, $key, $default);
+	}
+
 	/**
 	 * Hydrate the input data for the request.
 	 *