Description of problem:
hammer --output=csv nor hammer --output=json does not provide valid output in the requested format. 

Examples:

# hammer --output=csv job-invocation create --inputs="command=echo tYEzvrxBAG" --job-template="Run Command - Script Default" --search-query="name ~ my.host.com" 2> /dev/null
Message,Id
Job invocation 3 created,3
1 task(s), 0 success, 1 fail

# hammer --output=json job-invocation create --inputs="command=echo tYEzvrxBAG" --job-template="Run Command - Script Default" --search-query="name ~ my.host.com" 2> /dev/null
{
  "message": "Job invocation 4 created",
  "id": 4
}
1 task(s), 0 success, 1 fail

Version-Release number of selected component (if applicable):
6.12 (or lower) onwards

How reproducible:
always

Steps to Reproduce:
1.Run `hammer --output=csv job-invocation create` or `hammer --output=json job-invocation create`

Actual results:
There is an extra line on STDOUT that shows the result of the task. This prevents STDOUT from being parsed as JSON or CSV.

Expected results:
No extra line in the requested format.