fixed HTML validation errors found after JS insertion

Moved the `aria` attributes from the `a` to the `li` and changed the `role` to `option` as per @masterbee request.

Also fixed the `module` code because it was calling a `header` inside a `header`.

Still not validating at 100% because of the mobile menu but according to @masterbee we would need to rewrite this function to get this to validate.

Hope this is ok for my first JS change in WET.
Here is the text from WAI-ARIA for menuitem:

"

An option in a set of choices contained by a menu or menubar.

Authors MAY disable a menu item with the aria-disabled attribute. If the menu item has its aria-haspopup attribute set to true, it indicates that the menu item may be used to launch a sub-level menu, and authors SHOULD display a new sub-level menu when the menu item is activated.

Authors MUST ensure that menu items are owned by an element with role menu or menubar in order to identify that they are related widgets. Authors MAY separate menu items into sets by use of a separator or an element with an equivalent role from the native markup language."

http://www.w3.org/TR/wai-aria/roles#menuitem