Cuba’s Communist Party bent its own rules this week to promote an old-guard general to the organization’s top decision-making bodies, the latest in a number of recent changes reflecting the challenges of an aging military leadership’s grip on power. Army corps general Ramon Espinosa, 83, the first vice minister of the Cuban armed forces, became a member of the Communist Party Politburo and its Central Committee during a Party meeting on Tuesday. His designation goes against the Party’s own rules modified in its latest Congress last year to ban officials 60 years and older from holding a seat a…