Project restructure

[erick-otenyo]

Refactoring

• Move all src code into climweb directory. Climweb is now a python package that can be used as a base for developing climweb plugins. Climweb will not be able to support plugins, that extend its functionality
• Rewrite docker configurations
• Add celery for async tasks. This will eventually replace tasks run with django background task package
• Use Redis for caching and celery task queueing, instead of memcache that was only a cache
• Add plugin-boilerplate for use with cookiecutter
• untrack .vscode
• climweb version now set in version.py instead of init.py