Swallow exceptions on __del__ of event
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

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