refs: https://github.com/TryGhost/Team/issues/1446
- changed mail API tests to use the new e2e test framework
- added the missing retry test - which has the wrong response format :(
mail
refs https://github.com/TryGhost/Toolbox/issues/135
- Going though local utils allows to have the "withFrontend: false" flag applied only to the e2e-api test suites. This way we can gradually introduce the no-frontend change across all test suites