Add Archlinux support

This commit adds Archlinux support. This needs changes in nginx.conf.erb
template and manifests to support pid value set to `false` (this skips it from
nginx.conf). This is due to `-pid /run/nginx.pid` being hardcoded to Archlinux
template. If you specify pid additionally in `nginx.conf` then nginx fails to
start.
typo fixes & trailing whitespace cleanup