[portland] Creating an API with Metered Billing

[Jason Champion]

Thank you Jeff and Lennon for the links+info.

As an example, the YouTube Analytics API takes 1-3 minutes to shut off 
once you hit your maximum quota. In that time you can go over limit by 
up to about 1%, which seems like a pretty reasonable margin of error.

Plus they look like the "nice guy" for letting you have a few extra 
calls now and then. :)