Twitter is making its play for developers. At its first-ever Flight developer conference, Twitter CEO Dick Costolo announced a new developer toolkit aimed at helping developers build and make money off applications on the Twitter platform. Called Twitter Fabric, the bundle of services includes Twitter's Crashlytics application crash detecting service, and MoPub, the ad exchange network.With the new tools, Twitter officially throws its hat in the ring to compete with Facebook and Google for developers' time and attention.