Added pretty configuration inside dev_server config file (#2218)

Author: smondal

lib/install/config/webpacker.yml

@@ -69,6 +69,7 @@ development:
     disable_host_check: true
     use_local_ip: false
     quiet: false
+    pretty: false
     headers:
       'Access-Control-Allow-Origin': '*'
     watch_options:

test/dev_server_test.rb

@@ -35,6 +35,12 @@ def test_host_with_port
     end
   end
 
+  def test_pretty?
+    with_rails_env("development") do
+      refute Webpacker.dev_server.pretty?
+    end
+  end
+
   def test_default_env_prefix
     assert_equal Webpacker::DevServer::DEFAULT_ENV_PREFIX, "WEBPACKER_DEV_SERVER"
   end

test/test_app/config/webpacker.yml

@@ -60,6 +60,7 @@ development:
     overlay: true
     disable_host_check: true
     use_local_ip: false
+    pretty: false
 
 test:
   <<: *default