Update chapter07.rst

For the example to work, you have to use {% csrf_token %} and additional imports in views.py
Added short documentation about csrf_token

This is the first time csrf_token is used in the book, the short
explanation comes from the django tutorial, part 4, as my english is
kind of weak...
Added link to relevant chapters
Re: Python 3 and Django

Updated a couple of points in the 'Django and Python 3.0' admonition
section:
1. Made it clear that the compatibility issues exist for the 3.x
series, not just 3.0.

2. Made it clear that Django as of version 1.4 doesn't support Python
3.x

3. Changed the verb tense in a couple of places to made it fit the
context more appropriately.
ch10 'name__icontains' to 'title__icontains'
Fix doc icons path
Removed reference to obsolete comment system
Default INSTALLED_APPS contains other apps now.

Have added messages and staticfiles app to INSTALLED_APPS example, since they
are now included in the tuple by default.

Also, since the book does not deal with either of these, have changed the
wording slightly to emphasize that not all apps will be discussed later.
Url pattern now using url() for consistency
Update admin INSTALLED_APPS requirements to 1.4

django.contrib.messages is required for admin to work
properly. Else changing password for user throws
error.
Update chapter05.rst

new Django syntax in INSTALLED_APPS(settings.py)
Broken links fix

Broken links fix
Typo on broken links

Typo on broken links
Update broken links

Update broken links
Broken links fix on all chapters

Broken links fix on all chapters
fixing mistakes on links

fixing mistakes on links
Update 05.rst
Update 07.rst

Update 07.rst
Updating the 07 rst again for the 5th time

Updating the 07 rst again
Merge pull request #34 from jay754/master

Fixed lots of broken links