Alarms

```python
>>> # create an alarm with default properties
>>> alarm = Alarm(my_device)  # my_device is the SoCo instance on which the alarm will be played
>>> print alarm.volume
20
>>> print get_alarms()
set([])
>>> # save the alarm to the Sonos system
>>> alarm.save()
>>> print get_alarms()
set([<Alarm id:88@15:26:15 at 0x107abb090>])
>>> # update the alarm
>>> alarm.recurrence = "ONCE"
>>> # Save it again for the change to take effect
>>> alarm.save()
>>> # Remove it
>>> alarm.remove()
>>> print get_alarms()
set([])
```
I thought about that quite a bit. There are a couple of reasons really:

* This function might be called even before any SoCo instances have been created. I thought it would be better for the end user if they did not have to create an instance just to find out what alarms there were.

* It just didn't seem very user friendly to me to *require* a SoCo to be passed, though of course one *can* be passed. The alarms are not tied to any particular SoCo instance, so ```get_alarms()``` just looks better than ```get_alarms(soco)```.