Fixed #9722 - used pyinotify as change detection system when available

Used pyinotify (when available) to replace the "pool-every-one-second"
mechanism in `django.utils.autoreload`.

Thanks Chris Lamb and Pascal Hartig for work on the patch.

docs/releases/1.7.txt

@@ -343,6 +343,9 @@ Management Commands
   Django takes this information from your settings file. If you have configured
   multiple caches or multiple databases, all cache tables are created.
 
+* The :djadmin:`runserver` command now uses ``inotify`` Linux kernel signals
+  for autoreloading if ``pyinotify`` is installed.
+
 Models
 ^^^^^^