2015/04/13 Headlines: Obama, Castro Hold Historic Meeting at Americas Summit; Castro Calls for "Respectful Dialogue" with U.S. in First Americas Summit Appearance; Maduro Challenges Obama on Venezuela Sanctions; Saudi Arabia Rejects Iran Ceasefire Calls in Yemen; Pakistani Lawmakers Reject Involvement; Hillary Rodham Clinton Announces 2016 Presidential Bid; U.N. Seeks Aid for Displaced Residents of Yarmouk; Blackwater Operatives Face Sentencing for Nisoor Massacre; DOJ Prosecutors Differed on Charges; Hundreds Mourn Walter Scott in South Carolina; Tulsa Reserve Deputy Who Killed Unarmed Man is Wealthy Police Donor; 10 California Sherriff's Deputies Suspended for Beating Caught on Video; NYC: Ramsey Orta, Man Who Filmed Eric Garner Death, Freed on Bail