CLI creates migrations with timestamps in the past #108

When using CLI, it just copy-pastes migrations, which makes them appear "before" other user-migrations.

This trips the "migrations up" command and requires a flag to migrate.

I was counting on using timestamps to make the migration filename unique and rely on that fact to allow users to "update pgflow" by coping all migrations over.

Potential solution would involve matching only the filename part after the timestamp and implementing a CI check that will fail the build if you create a migration that is a duplicate when the timestamp part is stripped.