Use info from getlasterror whether a document has been updated or created.
Initial support to Group and Permission. The /admin can't be exec login in MongoDB yet. Only SQLsDB (SQLite,...)

This code work with django-mongoadmin pluggin.
Adding, adjust and transplant more methods to auth.User model
exposing mongoengine.django module
Add session expiration test (with django timezone support activated)
Fix django timezone support
Changed the inheritance model to remove types

The inheritance model has changed, we no longer need to store an array of
`types` with the model we can just use the classname in `_cls`.

See the upgrade docs for information on how to upgrade
MongoEngine/mongoengine#148
This change in how the variable is declared DESCRIPTION corrects problems
when running the command ``python setup.py bdist_rpm``
Inheritance is off by default (MongoEngine/mongoengine#122)
Merge branch 'master' into 0.8

Conflicts:
	docs/changelog.rst
	mongoengine/__init__.py
Add _instance to Embedded Documents

Fixes MongoEngine/mongoengine#139
Updated changelog
Adding QuerySet(read_preference=pymongo.ReadPreference.X) and QuerySet().read_preference() method to override connection-level read_preference on a per-query basis.
Added validation and tests
Added clean method to documents for pre validation data cleaning (MongoEngine/mongoengine#60)
Add value_decorator into SequenceField

Allows post processing of the calculated counter value.
Added none() to queryset (MongoEngine/mongoengine#127)
Updated index creation now tied to Document class ((MongoEngine/mongoengine#102)
Better implementation for none - MongoEngine/mongoengine#127
Removed deprecation warning  #55