Initial stab
Add an action to hook into.
Add campaign tracking
Move instantiation of i18n class to admin only
Refactored i18n class, removing the need to extend it.
Updated i18n module
Changed variable names for i18n module
Updated i18n submodule
Update submodule
Moved class registration to separate function, added a new required variable
Merge pull request #1759 from Yoast/i18n-module

Add a new i18n module