use window.onlanguagechange instead of mozSettings
Merge pull request #24 from zbraniecki/1013929-switch-to-onlanguagechange

Bug 1013929 - Use the languagechange event instead of a mozSettings observer. r=stas
Bug 992473 - Switch to use MutationObservers for DOM localization
lint cleanup
remove obsolete file
don't remove content from the node when data-l10n-id is removed
stop exposing observer for now
actually fire translateElement from translateFragment
apply reviewer notes
remove recustion
don't play with localizeNode for now, don't recreate MO on each retranslation and set the dir/lang on retranslation