pip executable expected as part of plugin install.

[D Jayachandran]

Hi,

Am using a Ubuntu version of linux for my development and ARIA does not find 
the correct path of pip during the plugin install.
To be precise this happens when pip freeze is executed.

    @staticmethod
    def _pip_freeze():
        """Run pip freeze in current environment and return the output"""
        bin_dir = 'Scripts' if os.name == 'nt' else 'bin'
        pip_path = os.path.join(sys.prefix, bin_dir,
                                'pip{0}'.format('.exe' if os.name == 'nt' else 
''))
        pip_freeze = subprocess.Popen([pip_path, 'freeze'], 
stdout=subprocess.PIPE)
        pip_freeze_output, _ = pip_freeze.communicate()
        assert not pip_freeze.poll()
        return pip_freeze_output

Now the question is why are we executing a pip command directly and not using 
pip as a library.


Regards,
DJ