Endpoint to fetch an Application's "Hits per Eternity" metric.

We have Endpoints under the "Analytics API" to fetch metrics (e.g. Hits) over a certain time of period.

However, the database on the 3scale SaaS is constantly purged and we cannot ensure over 1 year of data:

https://access.redhat.com/solutions/3676031

The "Hits per Eternity" metric seems to be an exception though and it's not purged periodically.

Hence, the request is to make this data available from the 3scale API.

Dev note

For usage stats, we can define a usage_values_for_eternitity method as an alternate path in https://github.com/3scale/porta/blob/4581223c9d11afeb04aace285ce8bcc8f7664612/app/lib/stats/views/usage.rb#L15 and use the key "stats/{service:id}/metric:id/eternity" in apisonator's redis.