Fix usage of state.show_sls for salt-ssh

Previously, this failed:

```
$ salt-ssh '*' state.show_sls test
example:
    - No matching sls found for 't' in env 'base'
    - No matching sls found for 'e' in env 'base'
    - No matching sls found for 's' in env 'base'
```

Now, it works!  The ``mods`` argument needed to be split for ``salt-ssh`, as it was in the ``salt.modules.state.show_sls`` function.  Previously, it was iterating through all chars in the string being inputted.