Merge pull request #507 from embark-framework/bug_fix/webpack-piling

kill webpack processes when they are done

lib/pipeline/pipeline.js

@@ -107,7 +107,7 @@ class Pipeline {
                     webpackProcess.send({action: constants.pipeline.build, file, importsList});
 
                     webpackProcess.once('result', constants.pipeline.built, (msg) => {
-                      webpackProcess.disconnect();
+                      webpackProcess.kill();
                       return next(msg.error);
                     });
                   },