Imports
- golang.org/x/net/context
- github.com/theupdateframework/notary/signer
- github.com/docker/distribution/context
- github.com/theupdateframework/notary/proto
- github.com/theupdateframework/notary/tuf/data
- github.com/theupdateframework/notary/trustmanager
- google.golang.org/grpc
- google.golang.org/grpc/codes