Replace handler to task in nginx role, for optional tasks

role tasks can't load "notify" when they are included from an other role task.
so it was replaced but NOT DRY
Fix pip with virtualenv param in uWSGI role
Fix ownership in Mezzanine dir

* set owner/group explicitly, not to be set root
Fix adding uwsgi/nginx confs for multiple target
Add  a role for python applications hosted by remote git repositories