A capability is the capacity to do something. Capabilities are embedded
within signed tokens that dictate who created them, and who they apply to.
Caps follow the object capability model, where possession of a valid
capability token is the canonical source of authorization. This is different
from an access control list approach where users authenticate, and their
current set of capabilities are stored within a database.
Create an rcan token that grants capabilities to a remote endpoint.
The local endpoint is the issuer (granter), and the remote endpoint is the
audience (grantee).