This should fix Errors like:

```
Error: Failed to apply catalog: Validation of Exec[Download Grafana]
failed: 'curl -s -L
http://grafanarel.s3.amazonaws.com/grafana-1.6.1.tar.gz | tar xz' is not
qualified and no path was specified. Please qualify the command or
specify a path. at /puppet/modules/grafana/manifests/install.pp:17
Wrapped exception:
'curl -s -L http://grafanarel.s3.amazonaws.com/grafana-1.6.1.tar.gz |
tar xz' is not qualified and no path was specified. Please qualify the
command or specify a path.
```
Enable influxDB storage backend for Grafana

You use InfluxDB Grafana to store dashboards.
grafanaDB: true marks it for use as dashboard storage (applicable for
InfluxDB & Elasticsearch)