* Add libffi to all Postorius images.
* Use Django less than a certain version.
* Fix the version constraint.
* Fix uwsgi configuration by using only processes.
Several Changes:
- Uwsgi now listens on two sockets 8080 for http protocol and 8000 for uwsgi protocol
- Add a read_timeout in documentation for Nginx configuration
- Expose 8024 properly in Core image
- Expose 8080 and 8000 both in Web image
- Rearange the commands to get even less number of layers.
- Add SIGINT as stop signal in web because uwsgi needs it shut down gracefully
- Enable threads in default uwsgi configuration
Fix#64, Fix#15
