[influx cli] Verbose output for SSL connection errors

[kostasb]

The following error output is returned from influx CLI when trying to connect to InfluxDB over HTTP, when the server only listens on HTTPS:

influx -host influxdb.domain.net -port 8086 -username user -password passwd
Failed to connect to http://influxdb.domain.net:8086
Please check your connection settings and ensure 'influxd' is running.

This is a common issue for users who do not specify the -ssl flag.

A note to check for https/ssl connection setting should be printed upon empty reply from server.

E.g.

Failed to connect to http://influxdb.domain.net:8086
Please check your connection settings and ensure 'influxd' is running. Add -ssl option to connect using https.

Alternatively, the CLI could automatically attempt to connect over SSL if an empty response is returned.