New PHP management

- New versions (7.x)
- PHP upstream name
- Sites can use : default PHP version, select first one by PHP version,
  select by upstream name
- Add PHP filter plugin

doc/php.md

@@ -1,18 +1,23 @@
 PHP
 ===
 
-- `nginx_php56` and `nginx_php70`: boolean if you need to preconfigure PHP (default: false)
-- `nginx_php##_sockets`: list of sockets (see bellow)
+`nginx_php`:
+  - `version`: (M) PHP version
+  - `upstream_name` (O)
+  - `sockets`: (O) socket list
+
+If `sockets` is not provided, if uses local unix socket (based on PHP version).
 
 You should see [Nginx upstream module doc](http://nginx.org/en/docs/http/ngx_http_upstream_module.html).
 
 Each socket have:
 
-- `unix_socket`
+- `unix`
+
+XOR
+
 - `host`
 - `port`
 - `weight`
 - `max_fails`
 - `fail_timeout`
-
-With default configuration, it works fine with PHP-FPM.