Move Canteen Static Data in Migration

[tobiasjungmann]

Moves the database initialization into the migration. The db initializer is not needed anymore. Furthermore, halve the database request can be deleted since we do not need to check whether the entry already exists in the table if the table is newly cleaned.

Logging is set to silent and only in case of errors the errors will be logged.

[CommanderStorm]

I have left some inline style comments, have fixed a typo and have added the migration to the migration.go

Overall, nice job

[tobiasjungmann]

I've also altered some of the older migrations to start the server on an empty database. It will be checked whether the table exists and if not, the new table will be created. @CommanderStorm please have a look at it that we are not overriding tables on the active database.

[CommanderStorm]

Overall, I would have merged this, exept for the added if !tx.Migrator().HasTable(&File{}) {
Why did you add them? (don't they kind of defeat the point of a migration?)

[tobiasjungmann]

The has table is not needed anymore, this was a relic of testing a successful migration.

[CommanderStorm]

LGTM 🎉