Add git name, email config and Yarn option alternative to Bower, plus add venvs check.

[juanfe]

• Add git config name and email asking to the user, if no name nor email were given it doesn't config.
• You can user -y to create Yarn project instead -b to use Bower.
• Check if there are venv to create virtualenvs.
• Delete the previous created project in case of run a second time.