hterm: add localization logic
hterm: add localization logic

We want to be able to display messages directly, so make sure they
can be localized properly.

BUG=chromium:717743

Change-Id: Icf0dfeebebb8adc1b3b32ccf43b8d49519fbaa5c
Reviewed-on: https://chromium-review.googlesource.com/810040
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Reviewed-by: Brandon Gilmore <adbfbaf7e4f927b45ce8ad3e5043a632414a833b@google.com>

chromium/hterm,chromium/hterm,chromium/hterm,chromium/hterm