build: Require vala to dist

Vala is needed to create the distribution tarball, otherwise
files that would be used when --enable-vala is used against the
tarball would fail because of missing files.
Updated Traditional Chinese translation(Hong Kong and Taiwan)
l10n: Add Japanese translation
core: Fix typo in error message

https://bugzilla.gnome.org/show_bug.cgi?id=704804