* merge migration
* rm migration versions
* rm unneeded migration test data
* create index w/postgres + crdb compatible syntax
* add default to offers.invitee_credit_duration_days
* changes so that schema matches from master to branch
* change to be crdb compatible
* add check to confirm db version
* mv version check to migration
* update tests
* add minversion to sadb migration, update tests
* confirm min version for all dbs in a migration
* add validate migration to sadb
* fix lint err
* rm min version check from migrate
* change sadb check
* hard code min db version
* fix comment
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