use boto requests instead of requests, the library

Fixes http://tracker.ceph.com/issues/10015

But also ensures that urls are correct and respected by patching the Python socket module with `httpretty`.

It also changes a few methods that no longer exist with the response object from `boto` that were caught by tests.
Just took a look to those classes and indeed, they mangle the path.

Making sure I get you correctly, do you think we should do the same as in `_build_request` for this one part or change how `_build_request` so that it doesn't use `build_base_http_request` ? (or both?)