Bump deps / Use async-each-series instead of async

* I updated dependencies and devDependencies.
* I replaced [async](https://github.com/caolan/async) with [async-each-series](https://github.com/jb55/async-each-series). it is similar to [`async.eachSeries`](https://github.com/caolan/async#eachSeries), but as a small module.
* I replaced [matchdep](https://github.com/tkellen/node-matchdep) with [load-grunt-tasks](https://github.com/sindresorhus/load-grunt-tasks).

Looks like you forgot to remove this.  Everything else looks good.