import csv into influxdb

implementation options:

invoke data-importer with each single uploaded csv after it has been saved

• easy to do, requires almost no changes to data-importer
• needs to establish influxdb connection for every csv file -> inefficient

invoke data-importer with an entire day and when uploading failed files

• a little harder to do business logic wise, currently mainly using for object do operation paradigm
• conserves db connection much better

implement with influxdb java driver

• conserves db connection perfectly
• significant development effort, especially because java api is much worse than python's. Only allows line protocol or single points afaict https://github.com/influxdata/influxdb-client-java/tree/master/client#synchronous-blocking-api.
• unified error handling

run data-importer with cron without any connection to sensor2graph

• would need to implement getting date
• easily leaks days if there are ever problems with sensor2graph