* sometimes API calls return with null/empty response bodies. thus,
wrap all API calls in a retry loop.
* calls that submit work in the form of "commands" now retrieve the
commandId from successful command submission, and track completion
of that command before returning control to calling context.
* model CM's process state and use that model to guide state
transitions more intelligently. this guards against, for example,
the start command failing with an error message like "Role must be
stopped".
* improvements to logging levels, avoid spamming logs with the
side-effects of retries at this and higher contexts.
* include references to API documentation, such as it is.
Signed-off-by: stack <stack@apache.org>