first stab at ads

Do not merge yet,
For review only now
no Wikia style globals. If we need them, I prefer we declare a store in the global Wikia object and inject variables in there. There is already `Wikia._state`, if you:
```javascript
Wikia.provide('_.state.legacyGlobals', {
  wgAdDriverUseEbay: 'whatever'
  // inject other globals
});
```
Then we can stop the pattern of dumping things in the global namespace