Create and hook up a facet for WDS orchestration

app/assets/javascripts/host_edit_extensions.js

app/controllers/wds_servers_controller.rb

app/models/concerns/foreman_wds/host_extensions.rb

app/models/concerns/foreman_wds/nic_extensions.rb

app/models/foreman_wds/wds_facet.rb

app/models/wds_server.rb

app/views/hosts/provision_method/wds/_form.html.erb

app/views/wds_images/_list.html.erb

app/views/wds_servers/_server_select.html.erb

db/migrate/20180426133700_add_wds_servers.rb

lib/foreman_wds/engine.rb