This PR adds a first draft of notifications in app, using Vue.
It's not ideal yet. I don't know how to make a kind of centralized system to call it from all the Vue files without having to add `<notifications group="main" position="bottom right" />` in all the Vue files. If someone can help there 😀
This replaces the old build system used by Laravel 5.3. If you had
a previous dev installation, you probably need to run those instructions
before doing any front end stuff:
```
rm -rf node_modules
rm package-lock.json yarn.lock
npm cache clear --force
npm install
```
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.
