Bug 953041 - Adding English, Chinese, and French translations for "skip" button.

Translations were copied from a visually-similar part of the FTU app (gaia/apps/communications/ftu/locales). There's no Arabic translation yet.
Merge pull request #15217 from Moz-TedC/master

Bug 953041 - Adding English, Chinese, and French translations for "skip" button, r=timdream