A jury has found longtime Balch & Bingham attorney Joel Gilbert and Drummond Co. executive David Lynn Roberson guilty in a public corruption case involving the bribery of former Alabama Rep. Oliver Robinson. The pair was found guilty on all six counts, which included conspiracy, bribery, three counts of honest services wire fraud and money laundering conspiracy. They were indicted last year on charges that they provided Robinson with a valuable and confidential consulting contract in exchange…