Document bookkeeper REST API

[gothub]

Create a Swagger API definition for the bookkeeper REST API.

[gothub]

@csjx I started a Swagger.io api description for bookkeeper, with '/quotas' and '/usages' almost complete. Should this be added to the bookkeeper documentation? The Swagger definition can be exported to html and other formats.
The definition is temporarily located at https://app.swaggerhub.com/apis/gothub/bookkeeper/1.0.0, until a newer location is determined.

[csjx]

@gothub - I think this is great. As we discussed earlier, developing the API on Swaggerhub with a DataONE account would be great for shared development. And yes, it should be referenced into the documentation, so I'll think about how to incorporate it into the RST files, or just reference it externally.

[csjx]

I've worked on proposed changes from @gothub 's initial documentation and temporarily added them here: https://app.swaggerhub.com/apis/csjx/dataone-bookkeeper/v1#/ . Once reviewed, I'll move this to the dataoneorg account on Swaggerhub.

[mbjones]

I've moved this to https://app.swaggerhub.com/apis/mbjones/dataone-bookkeeper/v1#/ for further editing in prep of the release.