Add missing dependency in emulated_hue component. (#5394)

* Add missing dependency in emulated_hue component.

On first startup after upgrade to 0.36, the emulated_hue componented failed to
start because the http component had installed the modules it depends on, in
this particular case 'aiohttp_cors' was missing.

* Include dependencies for the emulated_hue web server

Emulated_hue uses it's own 'web-server' component to handle hue related
discovery and config, so we need to make sure the required http modules are
made available before we are initialized.

We don't have to depend on the home-assistant http/api component because we do
not need to have the frontend to be initialized to handle emulated_hue, so we
can just import in the same set of requirements as the http component.

* Fix linting error