Updates to Apache wsgi file

 * check if _app_path is already in sys.path before appending it

 * switch to maintenance mode when Apache is reloaded and
   _maint_mode == True

 * abstract _app_path and _maint_mode to top of code and label it for
   editing

 * label _maint_file at top of maintenance-specific code for editing (if a
   custom page is being used)

 * stat maintenance page to pick up changes without server-reloading (but
   don't use inotify/etc because doing it portably without sourcing Django
   libs adds too much complexity to be worth it for one static page)

 * in non-maintenance mode there is a _tiny_ added cost of one
   var-assignment and one if-branch during server reload/restart, but
   actual requests have no extra overhead (the "application" function is
   unchanged)

 * in maintenance mode, for speed-reasons, global vars are used instead of
   arg-passing

 * update copyright year, and s/ISC/THE AUTHOR/ in copyright notice