This PR checks all active Action Cable documentation for typos and other
fixes. It aims to make sure that when Rails 5 is released, that the
Action Cable docs are up to snuff with the other documentation included
with Rails.
[ci skip]
Instead of depending on ApplicationCable::Connection being defined at initialize
we should inject it in the Railtie.
Thus we can kill more setup in the tests too.
We were explicitly referencing Rails.root in ActionCable::Server::Configuration.initialize,
thereby coupling ourselves to Rails.
Instead add `app/channels` to Rails' app paths and assign the existent files
to `channel_paths`.
Users can still append to those load paths with `<<` and `push` in `config/application.rb`.
This means we can remove the custom `Dir` lookup in `channel_paths` and the Rails
and root definitions in the tests.
Logging Action Cable to STDOUT caused the development log to see double
messages like this:
```
Started GET "/" for ::1 at 2015-12-17 15:21:34 -0500
Started GET "/" for ::1 at 2015-12-17 15:21:34 -0500
Processing by Rails::WelcomeController#index as HTML
Processing by Rails::WelcomeController#index as HTML
Rendered /welcome/index.html.erb (0.0ms)
Rendered /welcome/index.html.erb (0.0ms)
Completed 200 OK in 3ms (Views: 1.3ms | ActiveRecord: 0.0ms)
Completed 200 OK in 3ms (Views: 1.3ms | ActiveRecord: 0.0ms)
```
Now that Action Cable is part of Rails it doesn't need it's own logger
and will log to STDOUT via the local dev server here:
https://github.com/rails/rails/blob/master/railties/lib/rails/commands/server.rb
