Add /changes/{id}/revisions/{commit}/drafts

Draft comments can now be managed through the REST API endpoint:

  GET /changes/{id}/revisions/{commit}/drafts

  Returns all drafts on that commit by the caller, organized as an
  object mapping path name to a list of comment objects.

  DELETE /changes/{id}/revisions/{commit}/drafts/{id}

  Remove a draft comment.

  PUT /changes/{id}/revisions/{commit}/drafts/{id}

  Update the contents of a draft comment. This not only supports
  changing the text, but also moving the comment to a different
  line or to an entirely different file.

  PUT /changes/{id}/revisions/{commit}/drafts

  Create a new draft, with a new unique identifier returned.

Change-Id: I53eb11138fac4b29623885d01c4451f51aa5ff31
11 files changed