LP#1306675 TPAC maketext default handler

Fall back to an unitialized maketext handler, which defaults to the
template language, when OpenILS::WWW::EGWeb::I18N->get_handle fails to
return a response.

Note that why get_handle() returns undef is not yet known.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>