* added comment for pillar example
 * removed override releasever variable use for CentOS

* removed override releasever variable use for CentOS

Needed to add repo management because opensuse doesn't have nginx
in default repo

this is needed on archlinux where the pid file is set by systemd
not the nginx.conf file.

In the pillar file you just add
  pid:

an value of 'None' and no pid entry in nginx.conf.
this now works with every None value set in the pillar file

This reverts commit f6ba9ddb59.

the nginx.ng formula is only compatible with the upcoming feature
release, as noted here:

https://github.com/saltstack-formulas/nginx-formula#nginxng

This argument is only currently available in develop, and thus does not
belong in this formula at this time.