Adding Google Analytics to the page

[kingo55]

I think it'd be really useful for you guys to know how many people download the game + download the maps etc from the resources site.

At the very least, we should have Google Analytics on the page so you're armed with data on how to improve the site. We have a few options at our disposal here:

1. Use the existing GA code from the main site (recommended - but needs configuration in GA to differentiate each page e.g. '/' on resources domain may get confused with '/' on the main site otherwise)

2. Use a new GA code (not recommended - means you won't have a single view of the user as they pass between different OpenRA properties)