GigaOM writes, Dalton Caldwell, the man behind failed startups Imeem and PicPlz, recently ruminated on what he wished Twitter could have become. Now he’s moving ahead with his own paid alternative that promises to shun advertising and focus on customer trust. Caldwell unveiled his big venture called App.net in a lengthy blog post Friday and kicked off a month-long Kickstarter-esque pledge campaign aimed at testing his theory about the need for just such a platform. He’s looking to raise $500,000 from 10,000 people, which he thinks will be enough money to get started and also validate his...