ENH: add wsgi application

1. deploy/wsgi.py
ENH: upgrade datetime objects

1. use django.utils.timezone instead of datetime, date classes
ENH: use paginator for next and previous objects

next_submission(), previous_submission()
next_revision(), previous_revision()

Improve code using django.core.paginator
ENH: update slugify() import

from django.template.defaultfilters import slugify -->

from django.utils.text import slugify
BUG: fix wrong usage of os.path.normpath
ENH: use execute_from_command_line in manage.py

`execute_manager` is deprecated -- mentioned in django-1.4 release notes
update manage.py according to django-1.5
ENH: remove admin_media_prefix settings

admin_media_prefix is deprecated in django-1.4
Its used from static_url
ENH: enable clickjacking protection middleware