clean up development concurrency, make sure ports exist in dev mode

example/Procfile

@@ -1,2 +1,2 @@
-ticker ./ticker
+ticker ./ticker $PORT
 error  ./error

example/ticker

@@ -1,6 +1,6 @@
 #!/usr/bin/env ruby
 
 while true
-  puts "tick"
+  puts "tick: #{ARGV.inspect}"
   sleep 1
 end