Make log out log out user only from this device

API calls to action=logout logs you out from *all* your sessions,
including ones on Desktop. This is rather painful. Now it just
clears the local cookies and tokens, and hence logs the user out
only on this particular device.

Bug: 64177

Change-Id: I7ac07e4d7aaac1e5a10d44667e0c6064c08e0847
Merge "Make log out log out user only from this device"