Update etag and field serialization functions to take a HttpRequest.
Review Request #3471 — Created Nov. 3, 2012 and submitted
Update etag and field serialization functions to take a HttpRequest. generate_etag() and serialize_*_field() functions now takes a request parameter. This requires an update to all callers, and thus is not backwards-comptaible. It's needed for cases of serialiation that may have to take into account some detail of the request, such as whether we're using http or https.
Ran the Djblets and Review Board unit test suites (after appropriate changes in Review Board).