Allow plugins to register demon processes...

Allow plugins to register demon processes (https://github.com/discourse/discourse/commit/1d024f77a614177bf2cdaa18f7518b35eb5423fb)

config/unicorn.conf.rb

@@ -84,7 +84,7 @@ before_fork do |server, worker|
 
     sidekiqs = ENV['UNICORN_SIDEKIQS'].to_i
     if sidekiqs > 0
-      puts "Starting up #{sidekiqs} supervised sidekiqs"
+      server.logger.info "starting #{sidekiqs} supervised sidekiqs"
 
       require 'demon/sidekiq'
       Demon::Sidekiq.after_fork do
@@ -107,7 +107,7 @@ before_fork do |server, worker|
     end
 
     if ENV['DISCOURSE_ENABLE_EMAIL_SYNC_DEMON'] == 'true'
-      puts "Starting up EmailSync demon"
+      server.logger.info "starting up EmailSync demon"
       Demon::EmailSync.start
       Signal.trap("SIGTSTP") do
         STDERR.puts "#{Time.now}: Issuing stop to EmailSync"
@@ -115,6 +115,11 @@ before_fork do |server, worker|
       end
     end
 
+    DiscoursePluginRegistry.demon_processes.each do |demon_class|
+      server.logger.info "starting #{demon_class.prefix} demon"
+      demon_class.start
+    end
+
     class ::Unicorn::HttpServer
       alias :master_sleep_orig :master_sleep