[WIP] Automatic gettext calls on static texts in HAML

The **haml-magic-translations** gem automatically calls `_()` on all static texts in HAML files.
For string extraction see: https://github.com/potager/haml-magic-translations#extracting-strings-and-merging-translations
Again, what's this doing and why?  Unless my eyes are wrong, it looks identical to the gsub above.  Can we use a common method if they are the same?