Minor Issue: init paramter clientApiKey is misleading

[drcariel]

Considering that the Push service has an api key and client secret as separate values, users could get confused that you are not asking for the same in this parameter.

A change to simply apiKey would be more appropriate since there is only one api key for Analytics. Anywhere the parameter is referenced should be changed to put emphasis that this key is from your analytics service and needs to be created.