* mount gnocchi volume for gnocchi-api and gnocchi-statsd
* fix the failed of gnocchi-api
* use gnocchi user when running gnocchi-upgrade
* use the app.wsgi file in python path directly, rather than copy it to
/var/www/cgi-bin/gnocchi/app file
TrivialFix
Change-Id: Ie026b8f44cd8e9703bf115cebb4e2d50b114a3a2