locally track languages the reader can speak (alpha)

using localStorage keep a record of how many articles up to 100
a user has read in various languages - purpose is to identify
users who can speak multiple languages and suggest article translations
to them

Also hooks into when a user toggles to a different language via the language
selection module in beta

additional changes:
expose supportsLocalStorage in mf-settings.js

Change-Id: Ifbff8fca03b7fab23cf78114d9b9069d5a47a9a1