Dependencies for HTTP component have to be specified twice

[dryewo]

First in the component definition:

(def-http-component Http "api.yaml" [db tokens])

Then in the system map:

(system/http-system-map configuration
                        map->Http [:db :tokens]
                        :db (db/make-db (:db configuration))
                        :tokens (oauth2/map->OAUth2TokenRefresher ...))

Maintaining these two places is error-prone and non-beginner-friendly.
This also relates to #48.

[LappleApple]

Hey @dryewo, can we close this issue? It's from May 2016.

Or, we could add a "Help Wanted" label.

[Otann]

Was covered in #97