Claim anon feedback after sign up

After posting feedback, one of the CTA's (CTA4) encourages users to
create an account of login. This addition will, after having created an
account or having logged in, update the feedback they had just submitted
to reflect their id in the af_claimed_by column.

Change-Id: I388a2534875d86f08c7f505d927285a62f2ba7ae
Merge "Claim anon feedback after sign up"