Sometimes, the cleanup process happend AFTER vhosts are installed, which
resulted in no vhost declared.

Parsing declared vhosts in pillar and comparing to present files on the
server allows to remove only unwanted files.
Plus, files are kept in sites-available, and removed only in
sites-enabled.

First implementation of TOFS for:
nginx_config, passenger_config, servers_config and snippets
Introduced tplroot on modified files as well
Fixed GH link of nginx.conf file in docs/TOFS_pattern.rst
Fixed test for snippets name pillar

BREAKING CHANGE: all previous `nginx` based configurations must be reviewed;
`nginx.ng` usage must be promoted to `nginx` and any uses of the original
`nginx` will have to be converted.

Improvement - Disable reload of nginx when enabled=False (previously the nginx was always reloaded if settings.config != None; even with enabled=False)