added methods for upload_of.

system/validation/rules/upload_of.php

@@ -48,4 +48,27 @@ public function check($attribute, $attributes)
 		return true;
 	}
 
+	/**
+	 * Set the acceptable file extensions.
+	 *
+	 * @return Upload_Of
+	 */
+	public function has_extension()
+	{
+		$this->extensions = func_get_args();
+		return $this;
+	}
+
+	/**
+	 * Set the maximum file size in bytes.
+	 *
+	 * @param  int  $maximum
+	 * @return Upload_Of
+	 */
+	public function less_than($maximum)
+	{
+		$this->maximum = $maximum;
+		return $this;
+	}
+
 }