Updated travis.yml
Fixed objectId for DBRef
Improved import cache
Fixed reload issue with ReferenceField where dbref=False (MongoEngine/mongoengine#138)
Moved injection of Exceptions to top level
Updated docs thanks @mitar
Merge branch 'master' into 0.7
Added CONTRIBUTING.rst
Updates to the readme
can now use AuthenticationBackends with permissions.
Merge pull request #573 from garrypolley/master

Allow Django  AuthenticationBackends to work with Django user

Thanks @garrypolley
Merge branch 'master' of github.com:hmarr/mongoengine
Added Garry Polley to contributors list

hmarr/mongoengine#573
Updated URLField

handle unicode and custom validator (MongoEngine/mongoengine#136)
Fix loop
Unicode fix reverted but can have custom validator

MongoEngine/mongoengine#136
Allow updates with match operators (MongoEngine/mongoengine#144)
Unicode fix for repr (MongoEngine/mongoengine#133)
Updated test
Added chaining regression test (MongoEngine/mongoengine#135)