chore: upgrade babel to v6

tasks/gulp-tests.js

@@ -72,7 +72,7 @@ gulp.task('test:prepare:server', ['test:prepare:mongo'], () => {
   }
 });
 
-gulp.task('test:prepare:build', (cb) => {
+gulp.task('test:prepare:build', ['build'], (cb) => {
   exec(testBin('grunt build:test'), cb);
 });
 

tasks/taskHelper.js

@@ -20,7 +20,7 @@ export var conf = nconf;
  * its tasks.
  */
 export function kill(proc) {
-  ((pid) => {
+  let killProcess = (pid) => {
     psTree(pid, (_, pids) => {
       if(pids.length) {
         pids.forEach(kill); return
@@ -32,7 +32,9 @@ export function kill(proc) {
       }
       catch(e) { console.log(e) }
     });
-  }(proc.PID || proc.pid));
+  }
+
+  killProcess(proc.PID || proc.pid);
 };
 
 /*