Provide way to pass Descending Read option to the Walk command

[a-b]

While we were working on CLI story, we want to have retry behavior for when we fetch the "MostRecentEnvelope". To do this, we wanted to read envelopes in descending order using the walk function (which currently has retry logic).

We found descending read option not be supported under the current walk function. Current implementation sets the read options explicitly.

As a workaround, we will decorate the client.Read function which is passed to Walk(). We will have it add the descending read option, and get the one envelope we need.

As an alternative approach, we suggest you consider moving retry from Walk to the lower-level Read function.

CC: @bwasmith

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. Unfortunately, the Pivotal Tracker project is private so you may be unable to view the contents of the story.

The labels on this github issue will be updated when the story is started.