configure.ac: pass --with-gettext-package to tp-aw's configure

telepathy-account-widgets is a submodule, so it can be included by
multiple projects. If we don't have a different per-project
GETTEXT_PACKAGE we end up with different projects shipping .mo files
supposed to be installed in the same location.
telepathy-account-widgets: update submodule

This update is needed to fix an issue with translations, see
https://bugzilla.gnome.org/show_bug.cgi?id=707208