This makes Flavor.create() fail until the main database has had all
of its flavors migrated. Since we want to avoid any overlap or clashes
in integer ids we need to enforce this. The flavor API was poorly
designed in that it exposes this internal id. Luckily, flavor creation
is infrequent and flavor migration is fast.
The flavors in our database are hard-coded in the first migration,
which means we have to basically do the migration during every
unit test in order to avoid having a legacy environment. Since that
leaves us with deleted flavors in the DB (which screws up the DB
archiving tests), this adds a hard_delete flag to the migration to
do an actual purge of those from our database. What a mess.
Related to blueprint flavor-cell-api
Depends-On: I8ab03af9d2f4974f26a7f8487ec978caea957e45
Change-Id: Iea063448f43da1043d16dd521d255dd29a0e1bc5