404 error does not indicate what resource was not found

[briskt]

tfc-ops variables list -o org -w workspace -k key can return a 404 for at least two different reasons: (1) organization name not found, or (2) workspace not found. The error message provided does not look different in the two scenarios:

API returned an error.
	Method: GET
	URL: https://app.terraform.io/api/v2/vars?filter%5Borganization%5D%5Bname%5D=org&filter%5Bworkspace%5D%5Bname%5D=workspace
	Code: 404
	Status: 404 Not Found
	Request Body: 
	Response Body: {"errors":[{"status":"404","title":"not found"}]}

[briskt]

To provide a more helpful error message, tfc-ops would probably have to make two separate calls. One to check the validity of the organization name, and one to list the variables.

[briskt]

Closed by #68.