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: I2ebb5a34e4cf09577924b625cb729ffad06828e2
Signed-off-by: Juan Hernandez <juan.hernandez@redhat.com>