Run OpenHTF 1.3.0 through 1.6.1

Tests running an older pinned OpenHTF could not use the CLI at all. Every release from 1.3.0 onward now works the same way.

• Added support for OpenHTF 1.3.0 through 1.6.1, with the same measurements, validators, attachments and phase outcomes on every release.
• Fixed attachments being dropped on releases below 1.5.2.