The Islamic State (IS) group is battling swiftly toward a key Iraqi military base in Anbar – building on momentum from its recent takeover of Ramadi – in an apparent campaign to consolidate its control of the province.IS militants are pushing toward the al-Habbaniya air base, east of Ramadi, which is one of the Iraqi government’s few major staging areas in Anbar from which it can potentially launch counter-attacks.Iraqi Army forces began to retreat Thursday afternoon from the Juayb…