refactor: move `public` over to `app`
chore: bring `Gruntfile` up-to-date
refactor: parallelly run watch and server

Now you can run `grunt` for development and `grunt deploy` for
deployment
chore: track source files under `app`
chore: clean up names

* Use `main`, not `entry`
* Use `application`, not `app`
* Remove `globals` in default `harp.json`
feat: kill Harp server before starting anew
feat: add a bunch of recommended packages
docs: update doc to match new conventions
chore: keep name convention up to date
feat: add Karma

close #1
doc: add sample spec