Added support for needs_explicit_pk_field

Django 1.6b2 removed has_auto_field and replaced it with
needs_explicit_pk_field.  With just has_auto_field, inlines are unusable
in 1.6b2.  The needs_explicit_pk_field was also backported to Django
1.5, but I don't know what version that affects.  The change maintains
backwards compatibility by also checking has_auto_field.

I also added the needs_explicit_pk_field/has_auto_field check to the
stacked template in order to support models where the PK field is
editable.
Merge pull request #363 from rockymeza/needs_explicit_pk_field

Added support for needs_explicit_pk_field
added pre delete container for inlines, fixed #368
Added a new block called "admin_title" that allows for greater customization of the admin title on the main page
distinguished related-lookup icons with autocompletes (like in versions before)
Update docs about __unicode__ and __str__

Give 2 examples with both python 2 and 3 and explains __str__ and unicode__
Change encoding functions to new django 1.4/1.5

smart_str was renamed smart_bytes in django 1.5, but this also works with django 1.4.

The "f.__unicode__()" is unadapted for python 3 as python 3 doesn't accept __unicode__() method (__str__() is used instead).

Django provided a "smart_text" function to deal with that, with is also available in django 1.4 (see https://docs.djangoproject.com/en/1.5/topics/python3/ )

With this commit, code is ready for future, but more important it can deal with python 3 properly.
Only exposing the project models when the user is authenticated to tighten security.
Merge pull request #375 from mijamo/master

Add encoding compatibility with django 1.4/1.5 + Python 3
Merge pull request #377 from marcgibbons/feature/hide-models-unauth

Security update: Hide models from anonymous users (Versions 2.4.x)
Merge pull request #373 from therippa/master

Added a new block called "admin_title" that allows for greater customization of the main header title
added block messages to base.html, fixed #376
importing reduce from functools, fixed #374
Revert "importing reduce from functools, fixed #374"

This reverts commit 2e141b3b7f199d83aaa9a7905c62eab4420cdef5.
added autocomplete_term_adjust, fixed #371
import reduce from functors, fixed #374
minor fix with date time js, fixed #364
Merge branch 'stable/2.4.x'
grappelli template docs update
docs update