make bin/ansible error output consistent for shell module as for the command module when no arguments are given

Without this patch we have:
```
$ ansible -i localhost, all -m command
No argument passed to command module
$ ansible -i localhost, all -m shell
localhost | FAILED | rc=256 >>
no command given
```
With this patch the latter becomes:
```
$ bin/ansible -i localhost, all -m shell
No argument passed to shell module
```