WASHINGTON — Secret Service agents shut down a protest outside the White House on Monday where about 30 young protesters demanded President Barack Obama fire Attorney General Eric Holder. Agents on scene claimed a backpack abandoned on a sidewalk was a “suspicious package,” closing the Pennsylvania Avenue pedestrian mall in front of the White House, and the adjoining Lafayette Park, from protesters and tourists. All pedestrian traffic, including media, was forced to retreat to side streets. Officers roped the streets off with bright yellow crime scene tape and brought in bomb-sniffing K-9 dogs. After waiting on the sidewalk behind the...