sdk: Regenerate against the latest API

This patch regenerates the SDK using the latest API obtained from the
engine built from commit 71d093.

Relevant changes:

- Add "UsageMessage" class to represent detailed error messages returned
  by the engine.
- Document "async" and "grace_period.expire" parameters of relevant
  actions.
- Added "stop_time" attribute to VM class.

Change-Id: I465ac39e428b0bbd9f0ecd4552e035fbc051e8e7
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>