odoo-instance: Update command makes pull without referencing remote branch

[ebirbe]

When we do odoo-instance update the update does not bring the latest changes of the remote repository. It happens because the command executed is a pull without the remote branch argument.

To avoid this, the script should mention what remote branch it spect to retreive:

git pull vauxoo 8.0

Or should configure previously the remote upstream using the following command:

git branch -u vauxoo/8.0