Fix trial expiration

Separating plan_level from community to a new table for the sake of saving some data about when communities have changed their plan levels.
I see a couple (potentional) issues:

1. This is 100% our own hosting business specific code, and thus it should preferable not be in the public repository
1. For anyone else than us (e.g. open source installations) this piece of code can cause confusing, if their own marketplace that is running in their own Digital Ocean server starts to complain about trial expiration.