Tasks/Buckets provisioning

Hello,
i'm using grafana and influxdb.
While i can use

```
DOCKER_INFLUXDB_INIT_BUCKET=${INFLUXDB_BUCKET}
```

it is unclear how i can provision influxdb with:
1. Multiple buckets
2. Tasks with json file

Is this supported?

Start by reviewing the Docker image's existing handling of DOCKER_INFLUXDB_INIT_BUCKET and the documented provisioning options. Determine whether multiple buckets and tasks supplied as a JSON file are supported; done means the supported configuration is implemented or the limitation and usage are clearly documented.

Written by the indexing model from the issue text.