feat(vhosts): Better cleanup solution

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.

nginx/servers_config.sls

   file.directory:
     {{ sls_block(nginx.servers.dir_opts) }}
     - name: {{ nginx.lookup.server_enabled }}
-    - clean: {{ nginx.servers.purge_servers_config }}
 
 # If enabled and available are not the same, create available
 {% if nginx.lookup.server_enabled != nginx.lookup.server_available -%}
   file.directory:
     {{ sls_block(nginx.servers.dir_opts) }}
     - name: {{ nginx.lookup.server_available }}
-    - clean: {{ nginx.servers.purge_servers_config }}
 {%- endif %}
 
 # Manage the actual server files
 {%- endif %} {# enabled != available_dir #}
 {% endif %}
 {% endfor %}
+
+
+{# Add . and .. to make it easier to not clean those #}
+{% set valid_sites = ['.', '..', ] %}
+
+{# Take sites from nginx.servers.managed #}
+{% for server, settings in salt['pillar.get']('nginx:servers:managed', {}).items() %}
+{%   do valid_sites.append(server) %}
+{% endfor %}
+
+{% if salt['file.directory_exists'](nginx.lookup.server_enabled) %}
+{%   for filename in salt['file.readdir'](nginx.lookup.server_enabled) %}
+{%     if filename not in valid_sites %}
+
+{{ nginx.lookup.server_enabled ~ '/' ~ filename }}:
+  file.absent
+
+{%     endif %}
+{%   endfor %}
+{% endif %}