Correct various docstring typos and inaccuracies.
Review Request #8219 — Created June 4, 2016 and submitted — Latest diff uploaded
Fixes some miscellaneous docstring issues I've encountered across the code base: 1. In extensions.hooks.APIExtraDataAccessHook, fix a typo where 'private_data' was spelled incorrectly. 2. In webapi.tests.mixins_review, update a collection of HTTP PUT tests that were incorrectly labeled as HTTP POST.