Use application via ember-cli

It demonstrates full stack of the service. Unfortunately diff is too big but I can expain nuances.

I added JSON-router to `/api/checks` to connect Ember app. Ember app is placed in `<root>/ui` folder and could be executed by `ember server` with `snowman` in parallel (only for development). In production version the service uses minified assets which are build by command `./ui/release_new_ui`.

@keydunov review it please
Prefer double-quoted strings unless you need single quotes to avoid extra backslashes for escaping.