Move the Sidekiq reporter to after the logging middleware (bugsnag#326)

The Server::Logging middleware is the outermost middleware that Sidekiq provides by default.
This is a very safe place to put error reporting middleware, because any custom code implemented
by users of Bugsnag will probably not cause erroneous reports.

Closes bugsnag#326

lib/bugsnag/sidekiq.rb

@@ -27,10 +27,6 @@ def call(worker, msg, queue)
 
 ::Sidekiq.configure_server do |config|
   config.server_middleware do |chain|
-    if Gem::Version.new(Sidekiq::VERSION) >= Gem::Version.new('3.3.0')
-      chain.prepend ::Bugsnag::Sidekiq
-    else
-      chain.add ::Bugsnag::Sidekiq
-    end
+    chain.insert_after ::Sidekiq::Middleware::Server::Logging, ::Bugsnag::Sidekiq
   end
 end