Adding OAuth access scopes, fixing OAuth authorization UI, adding rate limiting

.rubocop.yml

app/assets/stylesheets/forms.scss

app/channels/public_channel.rb

app/controllers/api/v1/accounts_controller.rb

app/controllers/api/v1/follows_controller.rb

app/controllers/api/v1/media_controller.rb

app/controllers/api/v1/statuses_controller.rb

app/controllers/api_controller.rb

app/controllers/home_controller.rb

app/controllers/oauth/authorizations_controller.rb

app/models/feed.rb

app/models/media_attachment.rb

app/views/doorkeeper/authorizations/new.html.haml

app/views/doorkeeper/authorizations/show.html.haml

app/views/oauth/authorizations/error.html.haml

app/views/oauth/authorizations/new.html.haml

app/views/oauth/authorizations/show.html.haml

config/environments/production.rb

config/initializers/doorkeeper.rb

config/initializers/rabl_init.rb