Missing i18n strings

[BGMP]

We'll use this issue to keep track of missing i18n stuff.

• FAQ: All entries are missing their respective translation keys.
• Devise: We should regenerate the views using https://github.com/tigrish/devise-i18n for the keys to come in automatically. After doing that, we must then tidy up the views for them to match our current layout.
• Kaminari: Add missing translation keys.

[BGMP]

Although kaminari-i18n already extends support for several locales, it isn't fully compatible with the ones we've defined ourselves; regional locales such as es_cl, es_ar, etc. aren't working out of the box because they need kaminari's keys to be defined in their respective files.

This should just be a matter of copy-pasting these keys into config/locales/en.yml

[BGMP]

I'll take care of Kaminari, you keep working on devise @nickskyline