Use superagent for requests and make the API URLs more configurable

1 job for master in 1 minute and 5 seconds
Status Job ID Name Coverage
  Test
failed #219422351
jest

00:01:05

 
Name Stage Failure
failed
jest Test
      at Object.saveToCache (src/osm/element/cache.spec.js:8:11)

Test Suites: 1 failed, 1 total
Tests: 3 failed, 3 total
Snapshots: 0 total
Time: 0.925s
Ran all test suites.
npm ERR! Test failed. See above for more details.
ERROR: Job failed: exit code 1