Saudi Arabia on Wednesday unveiled plans to boost its oil-production capacity to help fight a price war with Russia, as other producers launched attempts to mediate a truce. The capacity increase comes after the kingdom instigated an oil-price war with Russia by signaling its intentions to boost production and slash prices. Russian Energy Minister Alexander Novak responded Tuesday, saying his country could rapidly open its own taps and add 500,000 barrels a day to its current production. …