global: implement idutils.from_url

Example:

```python
>>> idutuls.from_url('http://ui.adsabs.harvard.edu/#abs/2011ApJS..192...18K')
('ads', '2011ApJS..192...18K')
>>> idutuls.from_url('http://arxiv.org/abs/arXiv:1310.2590')
('arxiv', 'arXiv:1310.2590')
>>> idutuls.from_url('http://hal.archives-ouvertes.fr/inserm-13102590')
('hal', 'inserm-13102590')
```
