update moment.js to 2.7.0
i18n: add traditional chinese (taiwan) (by charles chuang)

While transifex and moment.js use the locale code zh_TW, babel claims
that zh_TW is not a real locale and zh_Hant_TW should be used instead
(search for "zh_TW" on http://babel.pocoo.org/docs/api/core/).

This is where all the soft links are coming from.
add zh_TW locale alias
Merge pull request #918 from xi/feature-i18n-zh_TW

translation: traditional chinese (taiwan)