FEATURE: set UNICORN_STATS_SOCKET_DIR for status socket

eg:

sam@ubuntu stats_sockets % socat - UNIX-CONNECT:9622.sock
gc_stat
{"count":46,"heap_allocated_pages":2459,"heap_sorted_length":2460,"heap_allocatable_pages":0,"heap_available_slots":1002267,"heap_live_slots":647293,"heap_free_slots":354974,"heap_final_slots":0,"heap_marked_slots":503494,"heap_swept_slots":498773,"heap_eden_pages":2459,"heap_tomb_pages":0,"total_allocated_pages":2459,"total_freed_pages":0,"total_allocated_objects":4337014,"total_freed_objects":3689721,"malloc_increase_bytes":6448248,"malloc_increase_bytes_limit":29188387,"minor_gc_count":36,"major_gc_count":10,"remembered_wb_unprotected_objects":19958,"remembered_wb_unprotected_objects_limit":39842,"old_objects":462019,"old_objects_limit":895782,"oldmalloc_increase_bytes":6448696,"oldmalloc_increase_bytes_limit":19350882}

lib/demon/sidekiq.rb

@@ -6,6 +6,10 @@ class Demon::Sidekiq < Demon::Base
     "sidekiq"
   end
 
+  def self.after_fork(&blk)
+    blk ? (@blk=blk) : @blk
+  end
+
   private
 
   def suppress_stdout
@@ -17,6 +21,8 @@ class Demon::Sidekiq < Demon::Base
   end
 
   def after_fork
+    Demon::Sidekiq.after_fork&.call
+
     STDERR.puts "Loading Sidekiq in process id #{Process.pid}"
     require 'sidekiq/cli'
     # CLI will close the logger, if we have one set we can be in big