Install & deployment documentation

* Adds a new toplevel section, in Master the CDN deployment document should be moved under setup/
* Adds installation documentation /cc @sle-odoo 
* Adds deployment documentation (very basic, will require extensions with examples) /cc @KangOl 
* Documents a few more CLI flags
* Reinstates support for `--no-xmlrpc`` which didn't work anymore, for CRON-only workers (WSGI deployments)
* Removes unused fname in configmanager
* Reindent werkzeug.wsgi.SharedDataMiddleware instantiation so it's only set up when there are static folders to expose

Won't be there for some time, so if you've got things you want changed or reverted, do so directly