anonymous event tracking slows down dbt runs when there is no internet connection

[drewbanin]

Issue

Issue description

dbt's anonymous event tracking will try to send events even when there is no internet connection. In these cases, each ping takes about a second to timeout, adding a meaningful amount of time to every run. This was actually the root cause of this issue: #1002

dbt should either try to fire these events in a background thread, or stop trying to send pings if the first one fails. I think the former is preferable, as these shouldn't be blocking calls even if the pings are successful.

Results

dbt blocked on sending anonymous events, whereas these events should not have measurably impacted the performance of a given dbt run.

System information

0.11.x

The operating system you're running on:
This happened in a Docker container, though I imagine it would happen on any OS

Steps to reproduce

Turn off your wifi and wait