Python rule 159

- Improving Python generators to detect and support `Django` and `SimpleHttpServers` systems.
- `Django` will choose correct `python` version Docker image. Will use `python 2.7` for the version *bellow* `Django 1.7.0` and `python 3.4` for versions *greater* than `Django 1.7.0`;
- better detected system message when `azk init`:
```bash
ᐅ azk init -f            
azk: `node` system was detected at '/home/julio/_git/variosExamples-azk/node010' as 'node010'
azk: `django` system was detected at '/home/julio/_git/variosExamples-azk/django15' as 'django15'
azk: `django` system was detected at '/home/julio/_git/variosExamples-azk/django17' as 'django17'
azk: `python` system was detected at '/home/julio/_git/variosExamples-azk/flask' as 'flask'
```