i18n: git-init basic messages

i18n: git-init basic messages

Change the user visible strings in init-db.c to use gettext
localizations. This only converts messages which needed to be changed
from "foo" to _("foo"), and didn't need any TRANSLATORS comments.

I haven't marked the messages in init_db_usage or init_db_options for
translation, since that would require additional changes in
parse-options.c. Those can be done later.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>