WASHINGTON — The White House on Wednesday ended a long-standing ban on tourists taking photos or using social media during public tours of the building. Michelle Obama made the announcement in a video posted on her Instagram account. “If you’ve been on a White House tour, you may have seen this sign,” she says, holding up a placard that states “No Photos or Social Media Allowed.” “Well, not anymore,” she adds, and then dramatically rips the sign in half. The White House said the more than 40-year-old ban was lifted because changes in camera technology make it possible to take high-quality photos using less light.