feat: nextTick instead of setImmediate, and fix sync in async (#136)

* fix: avoid sync callback in async function

* chore: fix linting

* chore: remove non jenkins ci

* refactor: use nextTick over setImmediate

* refactor: async/nextTick for better browser support

benchmarks/key-stretcher.js

@@ -25,7 +25,7 @@ async.waterfall([
 
   suite
     .on('cycle', (event) => console.log(String(event.target)))
-    .run({async: true})
+    .run({ async: true })
 })
 
 function setup (cipher, hash, secret) {