Bieber pitch! Teen crooner plays Hub

Bieware! Biebermania is taking over Boston today, as famously toss-coiffed Justin Bieber blows into town for his sold-out concert at the TD Garden.“The girls go nuts! They scream, they faint, they cry,” said five-time Bieber concert goer Jenna Isaacson, 15, of Beacon Hill. She won’t do any of that, though. “I want him to notice me for who I am, in a good way.”Bieber crowds have gotten so out of