CONCORD, N.H. — Postal workers in cities big and small protested in front of Staples stores on Thursday, objecting to the U.S. Postal Service’s pilot program to open counters in stores, staffed with retail employees. Rallies were planned at 50 locations in 27 states. In Concord, more than 100 boisterous workers donned bright blue shirts and lined a busy commercial road near a Staples store. “Union busting, we say no,” they chanted, “the Staples deal has got to go.” Last year, Framingham, Mass.-based Staples Inc.