Installs a given python package into a given virtual environment.

        :param str package_name:
        :param str venv_path:

def venv_install(self, package_name, venv_path):
        """Installs a given python package into a given virtual environment.

        :param str package_name:
        :param str venv_path:
        """
        self.logger.debug('Installing `%s` into `%s` ...' % (package_name, venv_path))
        self._run_shell_command('. %s/bin/activate && pip install -U %s' % (venv_path, package_name))