Share action provider

This is working with Titanium 3.3.0.GA - I've updated the minimum required SDK.

It is used like shown in the example:
```javascript
abextras.addShareAction({
  menu: e.menu,
  intent: intent
});
```

Actually really straight forward. If you finding any issues please let me know.

I'll also have a look at if it is possible to create own ActionProviders. For now, only Sharing is possible. But I'm sure this can be improved in the future.

Best, 
Manuel