Hotfix to master

[hansonkd]

Have you thought about adding the develop portion of

#MongoEngineConnectionDatastore

    def _query(self, **kwargs):
        try:
            from mongoengine.queryset import Q, QCombination
        except ImportError:
            from mongoengine.queryset.visitor import Q, QCombination

to master as a hotfix? The current master branch is breaking since it doesn't have proper restrictions on what version of mongoengine to use.

[mattupstate]

Released 1.6.1 which fixes this issue. Thanks for the reminder.