Group mem/cpu output of ps.top

This groups memory and cpu output of `ps.top`, which makes more sense especially when being used via the API and it turning into a response object. 

Results in output like:
```
    - cmd:
        - /usr/bin/python
        - /usr/bin/salt-minion
        - -l
        - debug
    - cpu:
        ----------
        system:
            0.1
        user:
            0.58
    - create_time:
        1391110543.81
    - mem:
        ----------
        rss:
            35491840
        vms:
            464912384
    - pid:
        23660
```