Remove new constraint from migration downgrade.

Remove the foreign key constraint for user_id. Whilst it is a foreign
key the constraint was not set in the previous schema. Also sets the
columns names to unicode as they were in previous schema.

Fixes: bug 1169381
Change-Id: I9b1ac5305622d68a7e124ba8100a4b8166b43af0
Merge "Remove new constraint from migration downgrade."