Change HTTP error 422 to 400 for strict HTTP compatibilty

See info:
https://stackoverflow.com/questions/16133923/400-vs-422-response-to-post-of-data/20215807#20215807
3 jobs for api-v0.8.4 in 4 minutes and 58 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #8010
api publish

00:02:55

 
  Test
passed #8011
test

00:01:24

 
  Deploy
failed #8012
deploy API to staging

00:00:38

 
Name Stage Failure
failed
deploy API to staging Deploy
No job log