Removed all mention of streaming until proper release.
Installed Webmock and VCR.

Preparing for testing against actual endpoints. It's much saner
to do this as when API changes, the tests will start failing.
Major cleanup:

* removed deprecated endpoints,
* introduced VCR and webmock (allows more precise tests),
* removed cheats in tests ('send'-ing private methods).

All in all, tests look worse, but that's because the previous
version of the test suite was cheating. Tests will become better
as the codebase improves with future refactoring.