LP#1710512 - OPAC js strings need to be i18n-izable

LP#1710512 - OPAC js strings need to be i18n-izable

Adds a way to translate displayed string messages, in OPAC
JS source code alerts and other outputs. This is done by having
js.tt2 include i18n-strings.tt2 which contains an explosed/global
JS blob variable called eg_opac_i18n. This is intended to work
in similar fashion as base_js.tt2 in the webstaff ng client.

Signed-off by: Cesar Velez <cesar.velez@equinoxinitiative.org>
Signed-off-by: Jason Stephenson <jason@sigio.com>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>
Conflicts:
	Open-ILS/src/templates/opac/parts/js.tt2