By Luke Baker and Paul Carrel BRUSSELS/FRANKFURT (Reuters) - Barely a year after European leaders set out an ambitious vision for the euro zone's future, progress has all but stalled and pressure is building for what may amount to a 'make or break' moment for the union. The idea of a roadmap setting out steps towards the deeper integration of the euro zone came about in early 2012, when the debt crisis was at its peak and there were legitimate fears that Greece could be forced out of the currency union, or that the whole European project could disintegrate. ...