The minimum version in practice used to be 0.50.0, however that can be
lowered by removing unneeded kwargs from a couple of functions.
- i18n.gettext() `install_dir` defaults to the localedir option, and
doesn't need to be manually overridden to that location
- configure_file() `install` defaults to true if `install_dir` is set,
and before 0.50 that was also the *only* way to mark it as installed
Removing both these kwargs means that there is more leeway with the minimum
required version.
