Another OAuth for GOPL

func Token(scopes []string) (token *oauth2.Token)

OAUTH TOKEN application service requires downloaded
[CLIENT] in

  ~/.goauth/client.json

Command line interface

Run "make" to build a CLI to print the access token, as for caching.

References

[UTIL] https://github.com/google/oauth2l

A copy of OAUTH2L/UTIL has been truncated to its
necessary and essential employment.  Note that GOOG
OAUTH2L UTIL has an APACHE license.

[CLIENT] https://console.cloud.google.com/apis/credentials