fix(session): session serializer to json
Use defaults when host and port are passed as None
Added app_label Meta attribute to MongoUser class
Added entry to AUTHORS
Test for testing invalid dict field value.
Patch for #491

Fix for issue #491, a bug in the permissions system.
Added regression test for bug with DictField and numeric keys.

When a DictField has numeric fields, BaseDocument._lookup_field doesn't
work correclty.
Fixed bug with numeric valuedict keys and BaseDocument._lookup_field().
Fixed bug for count method when _none is True 

If my queryset have elements example:

qs.all().count() => 10
q = qs.all().none()

the count in queryset "q" must be 0
q.count() => 0
Error in GenericReferenceField serialization was fixed
Python 2.5-2.6 compatibility fix
added BSONSerializer
Merge pull request #480 from mishudark/master

fix(session Issue #454): session serializer to json
Updated geo tests
Merge branch 'master' of github.com:MongoEngine/mongoengine
Updates to docs ref: #454, #480
Added Django 1.6 to travis Refs: #480, #454
Fixed distinct casting issue with ListField of EmbeddedDocuments (#470)
Merge pull request #483 from grampajoe/connection-defaults

Use defaults when host and port are passed as None
Updated Authors and changelog (#483)