AuthenticatedUserFunctionalTest: spoof strava auth interactions

[aaron-schroeder]

I keep getting locked out of my strava account because I accept permissions over and over during functional tests. Let's have the test user start out authorized, with a token in the database. There should be only one test hitting the strava auth screen.

I think this will involve modifying the app that's running in the other thread, or at least the state of its in-memory database.

I think stravalib has implemented something like this; check over there.