Bug 1100964 - Expose a wipe button from developer menu. r=?

https://bugzilla.mozilla.org/show_bug.cgi?id=1100964
We should do the same changes to `apps/settings/locales/device_type/tablet/settings.device.en-US.properties` and `apps/settings/locales/device_type/tv/settings.device.en-US.properties`.