Aditional validation

* ```Virgilio.prototype.namespace$``` was able to create namespaces without name, so I added namespace name validator to check it. 
* Any Virgilio method or property could be changed with ```Virgilio.prototype.extend$```, including namespaces
Perhaps something like:

```js
/^\w+(\.\w+)*$/
```

Or am I missing some scenario's with this one? I like the idea though!