fix(mk,dbpath): chown to 'mongodb'
feat(mk): install 'pip' and 'virtualenvwrapper' to have access to 'mkvirtualenv'
feat(mk): install python and pip
refactor(mk): task order
refactor(mk,pip,venv)
feat(pip): install pymongo
feat(py): add 'Hello World, Mongo Style' and 'Hello World on a Web Server'
docs(shell): update command for exercices

* 'Hello World, Mongo Style'
* 'Hello World on a Web Server'