Log Message:
Update ruby-gettext-setup to 0.28.

0.27
* Fix spelling on config-sample.yaml
* Allow pot task to take a filename
* (maint) Fix failing locale test
* Rake task to merge .pot files
* (PUP-7881) Put default locales at the front of available_locales

0.28
* (maint) Convert named parameters to hash
* (maint) Deleting transient fixtures