Remove warning / hack added due to JB moving developmentExecutable location

[bitspittle]

After Compose 1.4.1, JB changed where the development executable ended up, from "build/developmentExecutable" to "build/js/developmentExecutable". In order not to totally screw our users over who migrate up, we have some code that detects and responds to this case, but it's a hack, and the users really should be changing their conf.yaml ASAP.