Add Dockerfile for Arabic-English language pack
Add Dockerfile for Arabic-English language pack

This change adds a Dockerfile to build an image for Arabic to English
translation. The Dockerfile assumes that a base 'joshua' image already
exists and downloads the language package from online.

thammegowda/incubator-joshua,thammegowda/incubator-joshua,fhieber/incubator-joshua,fhieber/incubator-joshua,fhieber/incubator-joshua,thammegowda/incubator-joshua,fhieber/incubator-joshua,fhieber/incubator-joshua,fhieber/incubator-joshua,thammegowda/incubator-joshua,thammegowda/incubator-joshua,thammegowda/incubator-joshua,fhieber/incubator-joshua,thammegowda/incubator-joshua,fhieber/incubator-joshua,thammegowda/incubator-joshua,fhieber/incubator-joshua,thammegowda/incubator-joshua,thammegowda/incubator-joshua