cURL output dry run

[jonathanlloyd]

Current behaviour:
cURL output mode actually executes the request & outputs both the cURL form and the response

This is undesirable because:

• The cURL format won't be printed if no response is returned (e.g. network error)
• The cURL format cannot be piped into a shell/file for later execution

Desired behaviour:
The cURL output option should not execute the request, and should only print the cURL command without any other formatting