The DB has changed a lot in the last months. If we want to be able to
track how people are using the application, we need to add more statistics
at the instance level. This shouldn't be too hard on the DB to calculate those
every night at midnight.
This is the first part of the API. It supports most of contacts, as well as the
journal. This PR also brings Monica to Laravel 5.5, as the API required it with
the new concept of resources. It needs to run `php artisan migrate` as well as
`php artisan passport:keys` to generate the access tokens needed for the API.
This pull request adds support to multi users in one account. It also introduces the notion of subscriptions.
Accounts can now have multiple users.
Subscriptions are defined by a new env variable called REQUIRES_SUBSCRIPTION, and defaults to false. As promised, all the paid features on .com will be free if you download and host Monica on your own server.
