Bug 1023714 - [vertical homescreen] Cancel button is not localized after a long press on the homescreen

https://bugzilla.mozilla.org/show_bug.cgi?id=1023714

Gaia-try: https://tbpl.mozilla.org/?tree=Gaia-Try&showall=1&rev=0bb3b4d9ab81
Using `cancel` here is probably not going to end the world but the fact we need to copy the localization directly into the app sucks =/ If we don't have one already we should file a bug to fix this and do something similar to how shared js has locale files (but grouped in the web component) https://github.com/mozilla-b2g/gaia/tree/master/shared/locales