Add a python virtualenv component

[loicalbertin]

Pull Request description

Description of the change

Add a Python VirtualEnv component

Description for the changelog

• Python VirtualEnv component (GH-74)

Applicable Issues

Closes #74

[Loic-R]

Looks good ! However, deployment failed if we try to install python3 virtual environment and python 3 is not installed on the target compute. Maybe we should write that installing a python 3 venv require a machine where python3 is already installed.

[loicalbertin]

Yeah you are right, this component expects for at least a version of python to be installed so we can handle installation of pip generically using the easy_install module and then install virtualenv using pip module all that without relying on a system dependent package manager.
If we install python itself then we will probably do it using a package manager (specially if we have to deal with versions) and it will became distribution dependent.... I have to think about it.