"CBSN: On Assignment" airs Monday, August 14, at 10 p.m. ET/PT on CBS, and on our streaming network, CBSN.With over 3.5 million followers on Instagram, Iskra Lawrence is a true social media star. While she has many fans, she is also no stranger to vulgar comments that appear on her Instagram photos. The 25-year-old model says she does not let those...