urlparse fails with AZURE_BLOBS

## Summary

As libcloud uses `_` in scheme name, many popular libraries, eg urllib, fail to parse the URIs generated.

```
In [1]: from urllib.parse import urlparse

In [2]: urlparse('AZURE_BLOBS://data')
Out[2]: ParseResult(scheme='', netloc='', path='AZURE_BLOBS://data', params='', query='', fragment='')
```

Start by locating where libcloud generates the AZURE_BLOBS URI and trace how its schemes are defined. Compare that output with urllib.parse.urlparse using the example; done should be demonstrated by a regression test or documented behavior showing the generated URI parses as intended.

Written by the indexing model from the issue text.