Add eventlogging for SUL2 activity

Log when we attempt to autologin users with the SilentLogin method, and
when the user is logged in by the central check, so we can determine
how many users are not being auto logged in correctly.

Change-Id: I2ae7c85cff6d936e35fca7422ba4f254dcd5cc9c
Merge "Add eventlogging for SUL2 activity"