1.0.0-beta5

Added

• Client\TokenEndpointException (extends ClientException) with the status
  and the OAuth error code, thrown by ClientCredentialsTokenProvider when
  the token endpoint answers without a token.
• The ActionRequestStore contract checks that replacing a request under the
  same IRI moves it to the object it now concerns, in auditTrail() and
  pendingChanges().

Fixed

• Client\DeliveryVerdict::of() walks the chain of previous exceptions, so a
  transport failure the SDK client wrapped in a ClientException, or a
  token-endpoint outage, is Retry rather than Reject; refused credentials
  stay final (Drupal integration review, round 3).