fix minor bugs in TranslatableSetting

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
Add tests for TranslatableSetting.

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
remove an invalid variable setting that would break everything

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
Actually implement TranslatedSetting in nikola.py.

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>
Make use of LocaleBorg() by default.

Signed-off-by: Chris “Kwpolska” Warrick <kwpolska@gmail.com>