Create Database causes the InfluxDB Exporter to fail for "write-only" users.

[JonasKunz]

When a "write-only" user is used with the InfluxDB exporter and the create-database option is enabled, the issued CREATE DATABASE will fail due to the authorization. In this case the exporter assumes that there is a problem with the connection and does not attempt to write points to influx.

To solve this, we should simply ignore errors occuring during the CREATE DATABASE query.