removes output that can show secrets

Stops printing the body of the request to the token endpoint to avoid
showing sensitive information like the client secret. We can add support
for debug/verbose output or add obfuscation of the secret later, this is
just a quick fix to stop showing by default.

token_request.go

@@ -41,7 +41,6 @@ func (tReq *TokenRequest) Execute(tokenEndpoint string, httpClient *http.Client)
 	}
 
 	fmt.Fprintf(os.Stderr, "token endpoint: %s\n", tokenEndpoint)
-	fmt.Fprintf(os.Stderr, "token request body: %s\n", vals.Encode())
 
 	req, err := http.NewRequest("POST", tokenEndpoint, strings.NewReader(vals.Encode()))