Stop using Utils module

Background

I'd like to get rid of the Utils module in adblockpluschrome. Currently, adblockpluscore still uses Utils.appLocale (in order to target notification) and Utils.logError().

What to change

In lib/downloader.js, lib/filterStorage.js, and lib/notifications.js, replace Utils.logError() with console.error() and remove the import.

In lib/notifications.js add a locale property to the Notifications class, with the default value of "en-US", and use this property instead of Utils.appLocale.

In test/stub-modules/, remove the file utils.js.

Integration notes

Remove Utils module from adblockpluschrome.

The former value of Utils.appLocale must now be set explicitly via the new locale property of the notifications object, e.g. notifications.locale = "fr-FR".