A component for web apps that need access to services (stateful
components.) It mainly functions as a container for all the
components that the web app handlers need. It provides a middleware
to inject those components into ring requests.

To use, initialize by calling `app` with a config map (unused for
now) and a handler function. In your component system map, add any
other components that your app needs. Call `app-handler` with the
app component to return a handler wrapped in a middleware that will
inject all the components into the request map, under a
`::services` key, keyed by the same keys specified in the system map.

Handlers can use the `service` helper function to fetch a
particular service out of a request map.

Includes a prometheus ring middleware using iapetos and bidi.  Bidi's route
matching is required to remove route params from the time series.

This library does not include iapetos and bidi as dependencies directly, so
requiring this namespace will break unless you've done so yourself.

Ring request/response related specs.

Immutant web server component.