Fix Adjust Integration

Adjust events are associated to event tokens which are accessible via the Adjust Dashboard. For example, an "App Launch" event could be identified by a token "abc123".
We should pass Adjust event tokens rather than event names when calling `trackEvent:`.
The way I approached this is to allow passing a dictionary of event tokens mapped by event names when configuring `ARAnalytics` using the `ARAdjustEventTokenMap` key. Hence, the `AdjustProvider` will look up the proper token when `trackEvent:` is called.