Use httretty for mocking up machine translation tests

This way we don't rely on running services and also do not push too much
on them during heavy development.

Currently translated at 99.2% (953 of 960)

Currently translated at 34.6% (333 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

Currently translated at 100.0% (960 of 960)

This is a noun and not a verb

Currently translated at 99.2% (951 of 958)

Let's move checksum validation to the form, so that we can directly get
unit object out of that. This allows us to share more code between
different code paths.

Currently translated at 100.0% (958 of 958)