This is the first step in refactoring the Waiter and Retrier modules

* Moves wait into the Retrier module as wait_until, and renames
  the max parameter to max_duration, to convey that its purpose
  is similar to retry_until.
* Combines the loop logic into a single private method that the
  different public wait/retry methods use.
* Allows retry_until to retry up to a certain maximum time limit,
  like wait_until, as well as the original funtionality of waiting
  until a specified condition is met.
* Adds a retry_on_exception parameter to so that it's not necessary
  to nest wait/retry blocks if you want to do both.
* Adds a raise_on_failure parameter, which is the same as
  retry_until's exit_on_failure parameter, but now it can be used
  with wait_until.

Code review change to improve error message