go vet ./... reported some warnings, mainly that we were passing API

around by value (and therefore copying a RWLock). We weren't using the

RWLock in any of the functions that accepted API by value, but it is

more correct none-the-less to not copy the data around. We were,

however, passing API by value into a function that modified the token

store, but that is a pointer type so it worked. All methods of API now

take a pointer receiver.
We were also constructing composite literals (i.e., structs) without

naming the fields. We now avoid this everywhere.

Ran go fmt ./....
Ran go test ./....
Ran go vet ./....