[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
There's already an initializer for fast_gettext in initializers/fast_gettext.rb.  Can we just use that same file?