Performance of tests

[sadlerap]

With the release of v0.2.0, we've noticed that test runtimes can reach over an hour. Ideally, we'd like to have shorter test turnaround times. There are a few paths to investigate:

• Shorter polling times: in a lot of places, we wait 5s between polls in test steps. We can probably cut this down. Reduce default poll retry from 5s to 1s #38
• Parallelize tests: There isn't any reason we can't run tests in parallel.

[sadlerap]

#38 reduces test runtimes by about 20 minutes, give or take. There may be further performance benefits to be had.