Feature Request: Support FPM

[manuelmaurer]

All my webapps are served by nginx/fpm. Setting --server nginx will own the cache directories etc. by the nginx user although the files need to be writeable to the configuration user. To ease the process of deploying webapps do different users I added the fpm option to --server which uses the vhost_config_uid/vhost_config_gid values.

I am not a python programmer so this is just a quick-and-dirty patch:
fpm_patch.txt