One can access CurlRequest's NetworkReadStream in order to find out HTTP
response code or some other Stream-related data.
OneDriveTokenRefresher uses it to print some info on that 404 error I'm
trying to troubleshoot.
ConnectionManager now storages Request * (not generates ids for it),
Requests have control on their RequestState, RequestIdPair is now called
Response and storages Request * with some response together.
All related classes are changed to use it in more clean and
understandable way.
Request, RequestState and Response are carefully commented/documented.
Well, it takes two API calls instead of one now, but there are no
problems with expired token because of it.
This commit changes Storage::streamFile() to pass NetworkReadStream *
through callback.
OneDriveTokenRefresher is a CurlJsonRequest replacement for
OneDriveStorage methods. It behaves very similarly, but checks received
JSON before passing it to user. If it contains "error" key, it attempts
to refresh the token through OneDriveStorage, and then restarts the
original request, so user won't notice that there ever was an error.
