Encapsulation of casbin-cpp and other enhancements for pycasbin

Compared to Casbin for Golang, PyCasbin has many shortcomings, especially the lack of RBAC interface and its bad performance compared to Go. Therefore, parts such as performance need to be optimized. This proposal is mainly dedicated to implementing the encapsulation of casbin-cpp for pycasbin. In addition, this proposal also introduces the implementation of redis-adapter and etcd-adapter, the performance optimization of Enforce, the integration of Django and casbin, and the resolution of daily issues of casbin-cpp such as bugs and features to build a better access control system.