Fixes from notes

As promised, here's the list of things changed by this pull request (there's roughly one commit per item to make reviewing easier):

* some links to python docs point to version 2
* in install_python, the python3 version should be 3.4.1?
* in django_models, `default=timezone.now()` should be `timezone.now`
* `__unicode__` should be `__str__` (Python 3)
* in deploy, the .gitignore file should ignore `__pycache__` (python 3) instead of `*.pyc` (python 2)
* Links to Django docs should point to the version used (1.6)
* in django_forms, there's no need for the `{% load future %}`
* in django_forms, we could use shortcuts.redirect() instead of HttpResponseRedirect
* in domain, the google search link can be simplified (and moved to google.com instead of google.pl probably)