removes window.location.origin

window.location.origin isn't supported by Internet Explorer, according to [MDN](https://developer.mozilla.org/en-US/docs/Web/API/Window.location#Browser_compatibility).

This results in Spree.pathFor() not returning a absolute url.

eg.  ````Spree.pathFor('cart') => 'undefined/cart```` in IE

Whilst not as elegant as calling window.location.origin this solution returns the same value, and so allow ````Spree.pathFor()```` to work cross browser.