By Promit Mukherjee and David Ljunggren OTTAWA (Reuters) - The Bank of Canada reduced its key policy rate to a three-year low of 2.5% on Wednesday, the first cut in six months, and said it would be ready to cut again if risks to the economy increased in coming months. The 25-basis-point cut reflected a weak jobs market and less concern about underlying pressures on inflation, the bank said. It paused its easing campaign in March after reducing rates by a total of 225 basis points in nine months, startin ...