Freebird: the new go-recurly plugin

mostly pulled out of `go-subscriptions` and `go-subscriptions-freebies`.

see https://github.com/GigaOM/legacy-pro/issues/4125
weird! i'm not seeing what you're seeing...
![screen shot 2014-09-17 at 2 54 30 pm](https://cloud.githubusercontent.com/assets/3730514/4312022/4fcfb718-3eb5-11e4-9176-6ae133d07e32.png)