Promises wrapper does not include headers with error

[shpros]

We're getting 429s from methods as various as createDocument, queryCollections, and queryStoredProcedures. Until #39 is addressed, we would like to handle the retry ourselves, but we're using the promises flavor, which doesn't return the headers with the error. It would be great to have headers returned on error in the promises flavor. Currently, all of the deferred.reject() calls pass only the error, and swallow the headers, so we don't get the x-ms-retry-after-ms header or any other headers. See e.g. https://github.com/Azure/azure-documentdb-node/blob/master/q_promises_sdk/documentclientwrapper.js#L16

[shpros]

We'd like to fork and take a crack at this if that's ok.

[ghost]

Absolutely. We'd love to accept contributions from the community.

[shpros]

Great, we should have a PR for you soon.

[BillAtPros]

PR #46 submitted.

[ghost]

Thanks, we'll take a look shortly.

[BillAtPros]

Bump.

[ghost]

Sorry for the delay in getting to this. I will chase up the reviewers now.

[ghost]

Closed with PR #46