NEW YORK - Striking bus and subway workers agreed Thursday to "take steps" to go back to work while their union and the transit authority resume negotiations, a mediator said. The deal with the Transit Workers Union could pave the way for a resumption in service by Friday, if the union's executive board gives the final OK. The strike, the system's first in 25 years, halted service for millions. "Both parties have a genuine desire to resolve their differences," said Richard Curreri, head of a three-member state mediation panel. "They have agreed to resume negotiations while the TWU takes steps...