fixed: when upload fails, the upload button is not re-enabled, closes https://github.com/kobotoolbox/enketo-express/issues/247
fixed: when upload fails, the upload button is not re-enabled,
closes https://github.com/kobotoolbox/enketo-express/issues/247

pfitzpaddy/ngm-enketo-express,kevinmwangi/enketo-express,sdibona/enketo-express-oc,enketo/enketo-express,sdibona/enketo-express-oc,pfitzpaddy/ngm-enketo-express,hossein/enketo-express,dozymoe/enketo-express-oc,kevinmwangi/enketo-express,dozymoe/enketo-express-oc,OpenClinica/enketo-express-oc,enketo/enketo-express,kobotoolbox/enketo-express,kobotoolbox/enketo-express,sdibona/enketo-express-oc,ivansugi/enketo-express-oc,onaio/enketo-express,enketo/enketo-express,dozymoe/enketo-express-oc,onaio/enketo-express,kobotoolbox/enketo-express,ivansugi/enketo-express-oc,hossein/enketo-express,kobotoolbox/enketo-express,sdibona/enketo-express-oc,OpenClinica/enketo-express-oc,pfitzpaddy/ngm-enketo-express,onaio/enketo-express,ivansugi/enketo-express-oc,hossein/enketo-express,OpenClinica/enketo-express-oc,kevinmwangi/enketo-express,hossein/enketo-express