Analytics Loader pulls data for merchant/reseller/stack from GA Reporting API

The current loader reads the reports from an email folder. This works, and for resellers who do not want to grant us access to their GA account, it is our only option. Unfortunately this means we just have to wait around for data and we get it whenever GA gets around to sending it. We will want to continue to support this method.

For other resellers we would prefer to use the GA Reporting API which allows us to pull data directly along with a 'isDataGolden' flag that is meant to tell us if the data is unlikely to change in the future.

There are other future benefits to using the GA Reporting API, but the ability to schedule our downloads and know when the data is reliable are the biggies for Saturn.

Ideally this would be implemented as a REST service endpoint. If the endpoint cannot get data from the API for the given reseller, it should look for the latest data downloaded from the email job and return that. The response should say where the data came from and have date information.