allow with_limit_and_skip to be passed to cursor count method
Merge pull request #92 from texuf/master

searching for {'propertyName' : None}  and {'propertyName.subProp' : Non...
Merge pull request #93 from emirose/cursor_count_method_with_arg

allow with_limit_and_skip to be passed to cursor count method
Credits
add group and aggregate functions
fix parameters on group and aggregate to match pymongo