Recap: The Astros rallied from a 4-0 seventh-inning deficit to down the Washington Nationals 6-4 Monday during a Grapefruit League game in Kissimmee, Fla. Astros first-base prospect Jonathan Singleton smoked a bases-clearing, three-RBI triple to deep center field during a five-run seventh. “It was a fastball in the middle part of the plate and I just tried to put a good swing on it,” Singleton said. Big bat: Fernando Martinez went 2-for-3 on the same day the Astros announced he’d made the 25-man opening-day roster. Starter: Astros righthander Alex White, who is competing for the No. 4 spot in the rotation, allowed nine hits and four earned runs in five [...]