DEV: Add env variable to allow easier debugging of smoke tests

Set `DEBUG_NODE=1` when running `rake smoke:test` and use your favorite tool to debug the smoke tests. See https://nodejs.org/en/docs/guides/debugging-getting-started/ for more information.

The debugger will break at the beginning of the smoke tests when the env variable is set.

lib/tasks/smoke_test.rake

@@ -68,7 +68,12 @@ task "smoke:test" do
 
   results = +""
 
-  IO.popen("node #{Rails.root}/test/smoke_test.js #{url}").each do |line|
+  node_arguments = []
+  node_arguments << '--inspect-brk' if ENV["DEBUG_NODE"]
+  node_arguments << "#{Rails.root}/test/smoke_test.js"
+  node_arguments << url
+
+  IO.popen("node #{node_arguments.join(' ')}").each do |line|
     puts line
     results << line
   end