People across the country took to social media Sunday to commemorate what would have been Trayvon Martin’s 22nd birthday. Instead, the unarmed African-American teenager was shot and killed by white neighborhood watch vigilante George Zimmerman on February 26, 2012, sparking nationwide protests. On Tuesday, a new book written by Trayvon Martin’s parents will be published. It’s titled “Rest in Power: The Enduring Life of Trayvon Martin.”