Misc cleanup
Move "low" to separate line-- everything else is
Add a "namespacedevent" object, this give a convinent wrapper for firing events within a specific namespace
Refactor-- now all the event firing is done within low()

This means that *all* runner/wheel executions will have events
Swallow exceptions on __del__ of event

This will avoid exception in interpreter shutdown such as:

```
Exception TypeError: 'an integer is required' in <bound method MasterEvent.__del__ of <salt.utils.event.MasterEvent object at 0x3ab2a50>> ignored
```

Most of which are because during interpreter shutdown there is no order gaurantee so things (such as the zmq lib) get unloaded even though the __del__ method has references to it