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
Oh weird. Probably a rendering bug. I'm seeing them at the same tab level as the li:

![screen shot 2014-09-17 at 8 09 56 am](https://cloud.githubusercontent.com/assets/430385/4303218/99aac19a-3e63-11e4-9dda-0b7af8c00032.png)