bos: remove overdue concept and introduce account transitions

The table analytics_subscriptions contains blocking state information for bundles
and subscriptions. Let's introduce the table analytics_account_transitions which will
be a historic table for accounts, and will capture an account blocking states history.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
invoices: fix service period end date computation for fixed items

The previous implementation wasn't respecting changes during trials.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>