#64 add list to menu

- bulk add list to menu

as mentioned on previous pull request (merged by Tan) - https://github.com/Link7/virtual-pages-with-templates/pull/74, VPT now has a capability to add multiple Virtual Menu.

By navigating through `Appearance > Menus > Virtual Page` (new metabox).

Simply add the titles of the Virtual Pages you'd like to a appear to the menu.

![vptmenu](https://cloud.githubusercontent.com/assets/2107541/3336571/377f038e-f834-11e3-8bd9-c0fdb694dc52.jpg)

For your review @KarelOK