Added Service support for Oracle Enterprise Linux

I was getting the following error when trying to start services during the ```state.highstate```:

```
---------
    State: - service
    Name:      ntpd
    Function:  running
        Result:    False
        Comment:   An exception occured in this state: Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/salt/state.py", line 1206, in call
    *cdata['args'], **cdata['kwargs'])
  File "/usr/lib/python2.6/site-packages/salt/states/service.py", line 242, in running
    changes = {name: __salt__['service.start'](name)}
  File "/usr/lib/python2.6/site-packages/salt/modules/service.py", line 59, in start
    cmd = os.path.join(grainmap[__grains__['os']],
KeyError: 'OEL'
```